Small form factor telephoto camera

ABSTRACT

A compact telephoto lens system that may be used in a small form factor cameras. The lens system may include five lens elements with refractive power. Alternatively, the lens system may include four lens elements with refractive power. At least one of the object side and image side surfaces of at least one of the lens elements is aspheric. Total track length (TTL) of the lens system may be 6.0 mm or less. Focal length f of the lens system may be at or about 7.0 mm (for example, within a range of 6.5-7.5 mm). Lens elements are selected and configured so that the telephoto ratio (TTL/f) satisfies the relation 0.74&lt;TTL/f&lt;1.0. Materials, radii of curvature, shapes, sizes, spacing, and aspheric coefficients of the lens elements may be selected to achieve quality optical performance and high image resolution in a small form factor telephoto camera.

This application is a continuation of U.S. patent application Ser. No.14/069,027, filed Oct. 31, 2013, which is hereby incorporated byreference herein in its entirety.

BACKGROUND

1. Technical Field

This disclosure relates generally to camera systems, and morespecifically to high-resolution, small form factor telephoto camerasystems.

2. Description of the Related Art

The advent of small, mobile multipurpose devices such as smartphones andtablet or pad devices has resulted in a need for high-resolution, smallform factor cameras for integration in the devices. However, due tolimitations of conventional camera technology, conventional smallcameras used in such devices tend to capture images at lower resolutionsand/or with lower image quality than can be achieved with larger, higherquality cameras. Achieving higher resolution with small package sizecameras generally requires use of a photosensor with small pixel sizeand a good, compact imaging lens system. Advances in technology haveachieved reduction of the pixel size in photosensors. However, asphotosensors become more compact and powerful, demand for compactimaging lens system with improved imaging quality performance hasincreased.

SUMMARY OF EMBODIMENTS

Embodiments of the present disclosure may provide a high-resolutiontelephoto camera in a small package size. A camera is described thatincludes a photosensor and a compact telephoto lens system. Embodimentsof a compact telephoto lens system are described that may provide alarger image and with longer effective focal length than has beenrealized in conventional small form factor cameras. Embodiments of thetelephoto camera may be implemented in a small package size while stillcapturing sharp, high-resolution images, making embodiments of thecamera suitable for use in small and/or mobile multipurpose devices suchas cell phones, smartphones, pad or tablet computing devices, laptop,netbook, notebook, subnotebook, and ultrabook computers. In someembodiments, a telephoto camera as described herein may be included in adevice along with a conventional, wider-field small format camera, whichwould for example allow the user to select between the different cameraformats (telephoto or wide-field) when capturing images with the device.

Embodiments of a compact telephoto lens system are described thatinclude five lens elements with refractive power. In addition,embodiments of a compact telephoto lens system are described thatinclude four lens elements with refractive power. In embodiments, atleast one of the object side and image side surfaces of at least one ofthe lens elements is aspheric.

In at least some embodiments, the telephoto lens system may be a fixedtelephoto lens system configured such that the effective focal length fof the lens system is at or about 7.0 millimeters (mm) (e.g., within arange of 6.0-8.0 mm), the F-number (focal ratio) is within a range fromabout 2.4 to about 10.0, the field of view (FOV) is at or about 36degrees, and the total track length (TTL) of the lens system is within arange of about 5.2 to about 7.0 mm. More generally, the lens system maybe configured such that that the telephoto ratio (TTL/f) satisfies therelation:

0.74<TTL/f<1.0.

In the example embodiments described herein, the telephoto lens systemmay be configured such that the effective focal length f of the lenssystem is 7.0 mm, and the F-number is 2.8. However, note that the focallength (and/or other parameters) may be scaled or adjusted to meetspecifications of optical, imaging, and/or packaging constraints forother camera system applications. In addition, in some embodiments, thetelephoto lens system may be adjustable. For example, the telephoto lenssystem may be equipped with an adjustable iris or aperture stop. Usingan adjustable aperture stop, the F-number (focal ratio, or f/#) may bedynamically varied within some range, for example within the range of2.8 to 10. In some embodiments, the lens system may be used at fasterfocal ratios (f/#<2.8) with degraded image quality performance at thesame FOV (e.g. 36 degrees), or with reasonably good performance at asmaller FOV.

The refractive lens elements in the various embodiments may be composedof plastic materials. In at least some embodiments, the refractive lenselements may be composed of injection molded optical plastic materials.However, other suitable transparent materials may be used. Also notethat, in a given embodiment, different ones of the lens elements may becomposed of materials with different optical characteristics, forexample different Abbe numbers and/or different refractive indices.

In embodiments of the compact telephoto lens system, the lens elementmaterials may be selected and the refractive power distribution of thelens elements may be calculated to satisfy a lens system effective focallength requirement and to correct chromatic aberrations and the fieldcurvature or Petzval sum. The monochromatic and chromatic variations ofoptical aberrations may be reduced by adjusting the radii of curvatureand aspheric coefficients or geometrical shapes of the lens elements andaxial separations to produce well-corrected and balanced minimalresidual aberrations, as well as to reduce the total track length (TTL)and to achieve quality optical performance and high image resolution ina small form factor telephoto camera.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional illustration of an example embodiment of acompact telephoto camera including a compact telephoto lens system thatincludes five refractive lens elements.

FIG. 2 illustrates a plot of the polychromatic ray aberration curvesover the half field of view and over the visible spectral band rangingfrom 470 nm to 650 nm for a compact telephoto lens system as illustratedin FIG. 1.

FIG. 3 is a cross-sectional illustration of another example embodimentof a compact telephoto camera including a compact telephoto lens systemthat includes five refractive lens elements.

FIG. 4 illustrates a plot of the polychromatic ray aberration curvesover the half field of view and over the visible spectral band rangingfrom 470 nm to 650 nm for a compact telephoto lens system as illustratedin FIG. 3.

FIG. 5 is a cross-sectional illustration of another example embodimentof a compact telephoto camera including a compact telephoto lens systemthat includes five lens elements with refractive power.

FIG. 6 illustrates a plot of the polychromatic ray aberration curvesover the half field of view and over the visible spectral band rangingfrom 470 nm to 650 nm for a compact telephoto lens system as illustratedin FIG. 5.

FIG. 7 is a cross-sectional illustration of an example embodiment of acompact telephoto camera including a compact telephoto lens system thatincludes four lens elements with refractive power.

FIGS. 8, 9, and 10 show plots of the polychromatic ray aberrationscurves over the half field of view (HFOV) over the visible spectral bandranging from 470 nm to 650 nm for embodiments of a compact telephotolens system as illustrated in FIG. 7.

FIG. 11 is a cross-sectional illustration of an example embodiment of acompact telephoto camera including a compact telephoto lens system thatincludes five lens elements with refractive power in which the aperturestop is located at the first lens element and behind the front vertex ofthe lens system.

FIG. 12 illustrates a plot of the polychromatic ray aberration curvesover the half field of view and over the visible spectral band rangingfrom 470 nm to 650 nm for a compact telephoto lens system as illustratedin FIG. 11.

FIG. 13 is a cross-sectional illustration of an example embodiment of acompact telephoto camera including a compact telephoto lens system thatincludes five lens elements with refractive power in which the aperturestop is located between the first and second lens elements.

FIG. 14 illustrates a plot of the polychromatic ray aberration curvesover the half field of view and over the visible spectral band rangingfrom 470 nm to 650 nm for a compact telephoto lens system as illustratedin FIG. 13.

FIG. 15 is a high-level flowchart of a method for capturing images usinga camera as illustrated in FIGS. 1, 3, 5, 11, and 13, according to atleast some embodiments.

FIG. 16 is a flowchart of a method for capturing images using a cameraas illustrated in FIG. 7, according to at least some embodiments.

FIG. 17 illustrates an example computer system that may be used inembodiments.

This specification includes references to “one embodiment” or “anembodiment.” The appearances of the phrases “in one embodiment” or “inan embodiment” do not necessarily refer to the same embodiment.Particular features, structures, or characteristics may be combined inany suitable manner consistent with this disclosure.

“Comprising.” This term is open-ended. As used in the appended claims,this term does not foreclose additional structure or steps. Consider aclaim that recites: “An apparatus comprising one or more processor units. . . ”. Such a claim does not foreclose the apparatus from includingadditional components (e.g., a network interface unit, graphicscircuitry, etc.).

“Configured To.” Various units, circuits, or other components may bedescribed or claimed as “configured to” perform a task or tasks. In suchcontexts, “configured to” is used to connote structure by indicatingthat the units/circuits/components include structure (e.g., circuitry)that performs those task or tasks during operation. As such, theunit/circuit/component can be said to be configured to perform the taskeven when the specified unit/circuit/component is not currentlyoperational (e.g., is not on). The units/circuits/components used withthe “configured to” language include hardware—for example, circuits,memory storing program instructions executable to implement theoperation, etc. Reciting that a unit/circuit/component is “configuredto” perform one or more tasks is expressly intended not to invoke 35U.S.C. §112, sixth paragraph, for that unit/circuit/component.Additionally, “configured to” can include generic structure (e.g.,generic circuitry) that is manipulated by software and/or firmware(e.g., an FPGA or a general-purpose processor executing software) tooperate in manner that is capable of performing the task(s) at issue.“Configure to” may also include adapting a manufacturing process (e.g.,a semiconductor fabrication facility) to fabricate devices (e.g.,integrated circuits) that are adapted to implement or perform one ormore tasks.

“First,” “Second,” etc. As used herein, these terms are used as labelsfor nouns that they precede, and do not imply any type of ordering(e.g., spatial, temporal, logical, etc.). For example, a buffer circuitmay be described herein as performing write operations for “first” and“second” values. The terms “first” and “second” do not necessarily implythat the first value must be written before the second value.

“Based On.” As used herein, this term is used to describe one or morefactors that affect a determination. This term does not forecloseadditional factors that may affect a determination. That is, adetermination may be solely based on those factors or based, at least inpart, on those factors. Consider the phrase “determine A based on B.”While in this case, B is a factor that affects the determination of A,such a phrase does not foreclose the determination of A from also beingbased on C. In other instances, A may be determined based solely on B.

DETAILED DESCRIPTION

Embodiments of a small form factor camera including a photosensor and acompact telephoto lens system are described. Various embodiments of acompact telephoto lens system including four or five lens elements aredescribed that may be used in the camera and that provide a larger imageand with longer effective focal length than has been realized inconventional compact cameras. The camera may be implemented in a smallpackage size while still capturing sharp, high-resolution images, makingembodiments of the camera suitable for use in small and/or mobilemultipurpose devices such as cell phones, smartphones, pad or tabletcomputing devices, laptop, netbook, notebook, subnotebook, and ultrabookcomputers, and so on. However, note that aspects of the camera (e.g.,the lens system and photosensor) may be scaled up or down to providecameras with larger or smaller package sizes. In addition, embodimentsof the camera system may be implemented as stand-alone digital cameras.In addition to still (single frame capture) camera applications,embodiments of the camera system may be adapted for use in video cameraapplications.

Several example embodiments of compact telephoto lens systems aredescribed, including embodiments with five refracting lens elements andembodiments with four refracting lens elements. FIGS. 1 and 3 showvariations on an example embodiment that includes five refracting lenselements. FIG. 5 shows another example embodiment that includes fiverefracting lens elements. FIG. 7 shows an example of an embodiment thatincludes four refracting lens elements. FIGS. 11 and 13 show exampleembodiments with five refracting lens elements in which the aperturestop is located differently than in the embodiments of FIGS. 1, 3, and5. Note, however, that these examples are not intended to be limiting,and that variations on the various parameters given for the lens systemsare possible while still achieving similar results. For example,variations on the embodiment that includes four refracting lens elementsshown in FIG. 7 are described.

The refractive lens elements in the various embodiments may be composedof a plastic material. In at least some embodiments, the refractive lenselements may be composed of an injection molded plastic material.However, other transparent materials may be used. Also note that, in agiven embodiment, different ones of the lens elements may be composed ofmaterials with different optical characteristics, for example differentAbbe numbers and/or different refractive indices.

Small Form Factor Telephoto Camera

In each of FIGS. 1, 3, 5, 7, 11, and 13, an example camera includes atleast a compact telephoto lens system and a photosensor. The photosensormay be an integrated circuit (IC) technology chip or chips implementedaccording to any of various types of photosensor technology. Examples ofphotosensor technology that may be used are charge-coupled device (CCD)technology and complementary metal-oxide-semiconductor (CMOS)technology. In at least some embodiments, pixel size of the photosensormay be 1.2 microns or less, although larger pixel sizes may be used. Ina non-limiting example embodiment, the photosensor may be manufacturedaccording to a 1280×720 pixel image format to capture 1 megapixelimages. However, other pixel formats may be used in embodiments, forexample 5 megapixel, 10 megapixel, or larger or smaller formats.

The camera may also include a frontal aperture stop (AS) located infront of (i.e., on the object side of) a first lens element. While FIGS.1, 3, 5, and 7 show the frontal aperture stop located at or near thefront vertex of the lens system, location of the aperture stop may becloser to or farther away from the first lens element. Further, in someembodiments, the aperture stop may be located elsewhere in the telephotolens system. For example, the aperture stop may be located at the firstlens element but behind the front vertex of the lens system as shown inFIG. 11, or between the first and second lens elements as shown in FIG.13.

The camera may also, but does not necessarily, include an infrared (IR)filter located between a last lens element of the telephoto lens systemand the photosensor. The IR filter may, for example, be composed of aglass material. However, other materials may be used. Note that the IRfilter does not affect the effective focal length f of the telephotolens system. Further note that the camera may also include othercomponents than those illustrated and described herein.

In the camera, the telephoto lens system forms an image at an imageplane (IP) at or near the surface of the photosensor. The image size fora distant object is directly proportional to the effective focal lengthf of a lens system. The total track length (TTL) of the telephoto lenssystem is the distance on the optical axis (AX) between the front vertexat the object side surface of the first (object side) lens element andthe image plane. For a telephoto lens system, the total track length(TTL) is less than the lens system effective focal length (f), and theratio of total track length to focal length (TTL/f) is the telephotoratio. To be classified as a telephoto lens system, TTL/f is less thanor equal to 1.

In at least some embodiments, the telephoto lens system may be a fixedtelephoto lens system configured such that the effective focal length fof the lens system is at or about 7.0 millimeters (mm) (e.g., within arange of 6.0-8.0 mm), the F-number (focal ratio, or f/#) is within arange from about 2.4 to about 10.0, the field of view (FOV) is at orabout 36 degrees (although narrower or wider FOVs may be achieved), andthe total track length (TTL) of the lens system is within a range ofabout 5.2 to about 7.0 mm. More generally, the telephoto lens system maybe configured such that that the telephoto ratio (TTL/f) satisfies therelation:

0.74<TTL/f<1.0.

In the example embodiments described herein (see FIGS. 1, 3, 5, 7, 11,and 13), the telephoto lens system may be configured such that theeffective focal length f of the lens system is 7.0 mm at referencewavelength 555 nm, and the F-number is 2.8. The lens system may, forexample, be configured with a focal length f of 7.0 mm and F-number of2.8 to satisfy specified optical, imaging, and/or packaging constraintsfor particular camera system applications. Note that the F-number, alsoreferred to as the focal ratio or f/#, is defined by f/D, where D is thediameter of the entrance pupil, i.e. the effective aperture. As anexample, at f=7.0 mm, an F-number of 2.8 is achieved with an effectiveaperture of 2.5 mm. The example embodiment may also be configured with afield of view (FOV) at or about 36 degrees. Total track length (TTL) ofthe example embodiments vary from about 5.6 mm to about 6.0 mm.Telephoto ratio (TTL/f) thus varies within the range of about 0.8 toabout 0.857.

However, note that the focal length f, F-number, and/or other parametersmay be scaled or adjusted to meet various specifications of optical,imaging, and/or packaging constraints for other camera systemapplications. Constraints for a camera system that may be specified asrequirements for particular camera system applications and/or that maybe varied for different camera system applications include but are notlimited to the focal length f effective aperture, F-number, field ofview (FOV), imaging performance requirements, and packaging volume orsize constraints.

In some embodiments, the telephoto lens system may be adjustable. Forexample, in some embodiments, a telephoto lens system as describedherein may be equipped with an adjustable iris (entrance pupil) oraperture stop. Using an adjustable aperture stop, the F-number (focalratio, or f/#) may be dynamically varied within a range. For example, ifthe lens system is well corrected at f/2.8, at a given focal length fand FOV, then the focal ratio may be varied within the range of 2.8 to10 (or higher) by adjusting the aperture stop assuming that the aperturestop can be adjusted to the F-number setting. In some embodiments, thelens system may be used at faster focal ratios (f/#<2.8) by adjustingthe aperture stop, with degraded image quality performance at the sameFOV (e.g. 36 degrees), or with reasonably good performance at a smallerFOV.

While ranges of values may be given herein as examples for adjustablecameras and lens systems in which one or more optical parameters may bedynamically varied (e.g., using an adjustable aperture stop),embodiments of camera systems that include fixed (non-adjustable)telephoto lens systems in which values for optical and other parametersare within these ranges may be implemented.

Referring first to embodiments as illustrated in FIGS. 1, 3, 11, and 13a compact telephoto lens system (110, 210, 510, or 610) of a camera(100, 200, 500, or 600) may include five lens elements (101-105 in lenssystem 110 of FIG. 1, 201-205 in lens system 210 of FIG. 3, 501-505 inlens system 510, 601-605 in lens system 610) with refractive power andlens system effective focal length f, arranged along an optical axis AXin order from an object side to an image side:

-   -   a first lens element L1 (101, 201, 501, or 601) with positive        refractive power having a convex object side surface;    -   a second lens element L2 (102, 202, 502, or 602) with negative        refractive power having either a convex or concave object side        surface;    -   a third lens element L3 (103, 203, 503, or 603) with negative        refractive power having a concave object side surface;    -   a fourth lens element L4 (104, 204, 504, or 604) with negative        refractive power having a concave object side surface; and    -   a fifth lens element L5 (105, 205, 505, or 605) with positive        refractive power having a convex image side surface.        In addition, at least one of the object side and image side        surfaces of the five lens elements is aspheric.

The lens systems 110, 210, 510, and 610 are configured such that thatthe telephoto ratio (TTL/f) satisfies the relation:

0.74<TTL/f<1.0.  (1)

The first lens element L1 of lens systems 110, 210, 510, and 610 mayhave positive refractive power and length f1 and may satisfy therelation

0.35<f1/f<0.45.  (2)

In at least some embodiments of lens systems 110, 210, 510, and 610, L1may be biconvex in shape with vertex radii of curvature R2 and R3 andwith a shape satisfying the condition,

−0.35<R2/R3<0,  (3)

where R2 is an object side radius of curvature of L1 and R3 is an imageside radius of curvature of L1.

The second, third, and fourth lens elements (L2, L3, and L4) of lenssystems 110, 210, 510, and 610 may have negative refractive power andnegative focal length f2, f3, and f4, respectively, and may satisfy thefollowing conditions:

−0.7<f2/f<−0.4, and −5.0<R4/R5<7.0,  (4)

−3.5<f3/f<−1.0, and −15.0<R6/R7<0.5,  (5)

−0.6<f4/f<−0.3, and −2.0<R8/R9<−0.5,  (6)

where:

-   -   R4 is an object side surface radius of curvature of the second        lens element L2 and R5 is the radius of curvature of an image        side surface of L2,    -   R6 is the radius of curvature of an object side surface of the        third lens element L3 and R7 is the radius of curvature of an        image side surface of L3, and    -   R8 is the radius of curvature of an object side surface of the        fourth lens element L4 and R9 is the radius of curvature of an        image side surface of L4.

The second lens element L2 may have a negative refractive power and mayeither have a negative meniscus or be biconcave in shape. An exampleembodiment where L2 is negative meniscus in shape and having a convexobject side surface is illustrated by lens element 102 in lens system110 of FIG. 1. An example embodiment where L2 has a concave object sidesurface and is biconcave in shape is illustrated by lens element 202 inlens system 210 of FIG. 3.

The fifth lens element L5 of lens systems 110, 210, 510, and 610 mayhave positive refractive power and positive focal length f5, and maysatisfy the following conditions:

0.5<f5/f<0.8, and −1.5<R10/R11<−0.5,  (7)

where R10 is the radius of curvature of an object side surface of thefifth lens element L5 and R11 is the radius of curvature is of an imageside surface of L5.

In at least some embodiments as illustrated in FIGS. 1, 3, 11, and 13,the first lens element L1 and the fourth lens element L4 may be composedof a material (e.g., a plastic material) having an Abbe number of V1.The second, third, and fifth lens elements L2, L3, and L5, may becomposed of a material (e.g., a plastic material) having an Abbe numberof V2. The Abbe numbers of the materials for the lens elements maysatisfy the condition,

30<V1−V2<35.  (8)

Referring now to embodiments as illustrated in FIG. 5, a compacttelephoto lens system 310 of a camera 300 may include five lens elements(301-305) with refractive power and lens system effective focal lengthf, arranged along an optical axis AX in order from an object side to animage side:

-   -   a first lens element L1 (301) with positive refractive power        having a convex object side surface;    -   a second lens element L2 (302) with negative refractive power        having a convex object side surface;    -   a third lens element L3 (303) with positive refractive power        having a convex object side surface;    -   a fourth lens element L4 (304) with negative refractive power        having a concave object side surface; and    -   a fifth lens element L5 (305) with positive refractive power        having a convex image side surface.        In addition, at least one of the object side and image side        surfaces of the five lens elements is aspheric.

The lens system 310 is configured such that the telephoto ratio (TTL/f)satisfies the relation:

0.74<TTL/f<1.0.  (1)

Lens system 310 of FIG. 5 differs from lens systems 110 and 210 of FIGS.1 and 3 in at least the following aspect. The third lens element L3(303) of lens system 310 has positive refractive power or positive focallength f3. The positive lens element L3 has vertex radii of curvature R6and R7, and satisfies the conditions

R6<R7, and 0<R6/R7<1.0,  (9)

where R6 is the radius of curvature of an object side surface of thethird lens element L3 and R7 is the radius of curvature of an image sidesurface of L3. The lens element L3 is a positive meniscus in shape andhas a convex object side surface.

In lens system 310, the first lens element L1 (301) may have positiverefractive power and length f1, and may satisfy the relation

0.35<f1/f<0.45.  (2)

In at least some embodiments, L1 may be biconvex in shape with vertexradii of curvature R2 and R3 and with a shape satisfying condition,

−0.35<R2/R3<0,  (3)

where R2 is an object side radius of curvature of L1 and R3 is an imageside radius of curvature of L1.

In lens system 310, the second lens element L2 (302) may have negativerefractive power and negative focal length f2, an object side surfaceradius of curvature R4 and an image side surface radius of curvature R5,and may satisfy the conditions

−0.7<f2/f<−0.4, and 0<R4/R5<6.0.  (10)

In lens system 310, the fourth lens element L4 (304) may have negativerefractive power and negative focal length f4, and may satisfy theconditions

−0.6<f4/f<−0.3, and −3.0<R8/R9<0,  (11)

where R8 is an object side surface radius of curvature of lens elementL4 and R9 is the radius of curvature of an image side surface of L4.

In lens system 310, the fifth lens element L5 (305) may have positiverefractive power and positive focal length f5, may have a convex imageside surface, and may satisfy the following conditions:

0.75<f5/f<1.2 and −1<R10/R11<0,  (12)

where R10 is the radius of curvature of an object side surface of thefifth lens element L5 and R11 is the radius of curvature of an imageside surface of L5.

In at least some embodiments of lens system 310, the first lens elementL1 and fourth lens element L4 may be composed of a material (e.g., aplastic material) having an Abbe number of V1. The second, third, andfifth lens elements L2, L3, and L5, may be composed of a material (e.g.,a plastic material) having an Abbe number of V2. The Abbe numbers of thematerials for the lens elements may satisfy the condition,

30<V1−V2<35.  (8)

Referring now to embodiments as illustrated in FIG. 7, a compacttelephoto lens system 410 of a camera 400 may include four lens elements(401-404) with refractive power and lens system effective focal lengthf, arranged along an optical axis AX in order from an object side to animage side:

-   -   a first lens element L1 (401) with positive refractive power        having a convex object side surface;    -   a second lens element L2 (402) with negative refractive power;    -   a third lens element L3 (403) with negative refractive power;        and    -   a fourth lens element L4 (404) with positive refractive power        having a convex object side surface.        In addition, at least one of the object side and image side        surfaces of the four lens elements is aspheric.

The lens system 410 is configured such that the telephoto ratio (TTL/f)satisfies the relation:

0.74<TTL/f<1.0.  (1)

In lens system 410, the first lens element L1 (401) may have positiverefractive power and length f1 and may satisfy the relation

0.35<f1/f<0.45.  (2)

In at least some embodiments of lens system 410, L1 may be biconvex inshape with vertex radii of curvature R2 and R3, and may satisfy thecondition,

−0.35<R2/R3<0,  (3)

where R2 is an object side radius of curvature of L1 and R3 is an imageside radius of curvature of L1.

In lens system 410, the second lens element L2 (402) may have negativerefractive power and negative focal length f2, may have an object sidesurface radius of curvature R4 and an image side surface radius ofcurvature R5, and may satisfy the conditions

−0.7<f2/f<−0.4, and 0<R4/R5<6.0.  (10)

In at least some embodiments, the lens element L2 may have a convexobject side radius of curvature R4 and a concave image side radius ofcurvature R5.

In lens system 410, the third lens element L3 (403) may have negativerefractive power and negative focal length f3, may have an object sidesurface radius of curvature R6 and an image side surface radius ofcurvature R7, and may satisfy the conditions

−0.7<f3/f<−0.4, and −500<R6/R7<20.  (13)

In various embodiments, the element L3 may have either a concave orconvex object side radius of curvature R6 and a concave image sideradius of curvature R7. In at least some embodiments, lens element L2and L3 may be spaced apart by an axial distance T5.

In lens system 410, the fourth lens element L4 (404) may have positiverefractive power and positive focal length f4, and may satisfy thefollowing conditions,

0.8<f4/f<1.5, and 0.0<R8/R9<1.0,  (14)

where R8 is an object side surface radius of curvature of lens elementL4 and R9 is the radius of curvature of an image side surface of L4.

In at least some embodiments of lens system 410, the first lens elementL1 and third lens element L3 may be composed of a material (e.g., aplastic material) having an Abbe number of V1. The second lens elementL2 and fourth lens element L4 may be composed of a material (e.g., aplastic material) having an Abbe number of V2. The Abbe numbers of thematerials for the lens elements satisfy the condition,

30<V1−V2<35.  (8)

In at least some embodiments of lens system 410, the lens elements L1and L2 may be arranged in close proximity such that the combination ofL1 and L2 may be considered as an air-spaced doublet lens L12 ofpositive refractive power or positive focal length f12. In at least someembodiments of lens system 410, the lens elements L3 and L4 may bearranged in close proximity such that the combination of L3 and L4 maybe considered as a doublet lens L34 having negative refractive power andnegative focal length of f34. The axial separation between L12 and L34may be given by T5.

Compact Telephoto Lens System

The following provides further details of various embodiments of acompact telephoto lens system that may be used in a small form factortelephoto camera in reference to FIGS. 1 through 10.

FIG. 1 is a cross-sectional illustration of an example embodiment of acompact telephoto camera 100 including a compact telephoto lens system110. Lens system 110 includes five lens elements (101-105) withrefractive power. Arranged along an optical axis AX of the camera 100from an object side to an image side (from left to right in the drawing)are an aperture stop AS, a first lens element L1 (101) with positiverefractive power having a convex object side surface and focal lengthf1, a second lens element L2 (102) with negative refractive power havinga convex object side surface and focal length f2, a third lens elementL3 (103) with negative refractive power having a concave object sidesurface and focal length f3, a fourth lens element L4 (104) withnegative refractive power having a concave object side surface and focallength f4, and a fifth lens element L5 (105) with positive refractivepower having a convex image side surface and focal length f5. The lenssystem 110 forms an image plane at a surface of a photosensor 120. Insome embodiments, an infrared (IR) filter may be located between thefifth lens element L5 and the photosensor 120.

Effective focal length of the lens system 110 is given as f. The totaltrack length (TTL) of the compact telephoto lens system 110 is thedistance on the optical axis AX between the object side surface of thefirst lens element L1 and the image plane. The lens system 110 isconfigured such that the telephoto ratio (TTL/f) of the lens system 110satisfies the relation:

0.74<TTL/f<1.0.

An aperture stop AS, which may be located at the front surface of lenselement L1, determines the entrance pupil aperture of lens system 110.The lens system 110 focal ratio or f-number f# is defined as the lenssystem 110 effective focal length f divided by the entrance pupildiameter. The IR filter may act to block infrared radiation that coulddamage or adversely affect the photosensor, and may be configured so asto have no effect on f.

Tables 1A-1C provide example values for various optical and physicalparameters of an example embodiment of a camera 100 and lens system 110as illustrated in FIG. 1. Tables 1A-1C may be referred to as providingan optical prescription for the lens system 110.

Referring to Tables 1A-1C, embodiments of lens system 110 coverapplications in the visible region of the spectrum from 470 nanometers(nm) to 650 nm with reference wavelength at 555 nm. The lens system 110effective focal length f shown in Table 1A is at 555 nm. The opticalprescription in Tables 1A-1C provides high image quality performance atf/2.8 over the 470 nm to 650 nm spectrum, for an effective focal lengthf of 7 millimeters (mm), covering 36 degrees field of view (FOV) (18degrees half FOV). The compact lens system 110, illustrated in FIG. 1and with optical prescription as shown in Tables 1A-1C, has a totaltrack length (TTL) of 5.7 mm, and a telephoto ratio (TTL/f) of 0.814.

The five lens elements L1, L2, L3, L4, and L5 of lens system 110 may becomposed of plastic materials with refractive indices and Abbe numbersas listed in Table 1B. As shown in Table 1B, in at least someembodiments of lens system 110, two types of plastic materials may beused for the lens elements. Lens elements L1 and L4 may be composed ofthe same plastic material with an Abbe number V1 of 56.1, and lenselements L2, L3, and may be composed of another plastic material with anAbbe number V2 of 23.3. Lens element L5, having positive refractivepower, is formed from plastic material with an Abbe number V2=23.3. Theapplication of these two plastic materials for the lens elements in lenssystem 110 enables lens system 110 to be optimized and corrected forchromatic aberrations over the visible spectral region. The lens elementmaterials may be chosen and the refractive power distribution of thelens elements may be calculated to satisfy the effective focal length fand correction of the field curvature or Petzval sum. The monochromaticand chromatic variations of optical aberrations may be reduced byadjusting the radii of curvature and aspheric coefficients orgeometrical shapes of the lens elements and axial separations asillustrated in Table 1C to produce well corrected and balanced minimalresidual aberrations. FIG. 2 illustrates a plot of the polychromatic rayaberration curves over the half field of view (HFOV=18 degrees) and overthe visible spectral band ranging from 470 nm to 650 nm for a compacttelephoto lens system 110 as illustrated in FIG. 1 and described inTables 1A-1C.

The optical prescription in Tables 1A-1C describes an example embodimentof a compact telephoto lens system 110 as illustrated in FIG. 1 thatincludes five lens elements with refractive power and effective focallength f, and in which a second lens element L2 has negative refractivepower or negative focal length f2 and a convex object side surface. Inaddition, lens element L2 of lens system 110 is negative meniscus inshape and has positive radii of curvature R4 and R5, where R4>R5, andR4/R5>1.0.

In the example embodiment of lens system 110 as described by the opticalprescription in Tables 1A-1C, the refractive powers of the lens elementsare distributed such that f1=2.713 mm, f2=−3.862 mm, f3=−21.521 mm,f4=−3.176 mm, and f5=4.898 mm. Lens element L1 is a biconvex lens withradii of curvature R2/R3=−0.172, and L2 has radii of curvatureR4/R5=5.772. Lens elements L3 and L4 are both biconcave in shape withradii of curvature R6/R7=−14.564 and R8/R9=−1.578, respectively. Lenselement L5 is biconvex in shape with radii of curvature R10/R11=−0.604.The aspheric coefficients for the surfaces of the lens elements in lenssystem 110 in the example embodiment are listed in Table 1C. Configuringlens system 110 according to the arrangement of the power distributionof the lens elements, and adjusting the radii of curvature and asphericcoefficients as shown in Tables 1A-1C, the total track length (TTL) ofthe lens system 110 may be reduced (e.g., to 5.7 mm as shown in Table1A) and aberration of the system may effectively be corrected to obtainoptical performance of high image quality resolution in a small formfactor telephoto camera 100.

FIG. 3 is a cross-sectional illustration of an example embodiment of acompact telephoto camera 200 including a compact telephoto lens system210. Lens system 210 includes five lens elements (201-205) withrefractive power. Lens system 210 may be viewed as a variation of lenssystem 110 of FIG. 1 and elements of the two lens systems 210 and 110may be similar. However, in lens system 210, the second lens element L2(202) has negative refractive power or negative focal length f2 and hasa concave object side surface.

Tables 2A-2C provide example values for various optical and physicalparameters of an example embodiment of a camera 200 and lens system 210as illustrated in FIG. 3. Tables 1A-1C may be referred to as providingan optical prescription for the lens system 210.

The optical prescription in Tables 2A-2C is for a lens system 210 withan effective focal length f of 7 mm at 555 nm wavelength, a focal ratioof f/2.8, with 36 degrees FOV, TTL of 5.7 mm, and with TTL/f equal to0.814. Lens system 210 is a compact imaging lens system designed for thevisible spectrum covering 470 nm to 650 nm.

The lens elements L1, L2, L3, L4, and L5 of lens system 210 may becomposed of plastic materials with refractive indices and Abbe numbersas listed in Table 2B. In this example embodiment of lens system 210,the choice of lens materials are the same as in the optical prescriptionfor lens system 110 as listed in Tables 1A-1C. Referring to lens system210, the lens elements L1 and L4 may be composed of a plastic materialhaving an Abbe number of V1=56.1. The lens elements L2, L3, and L5 maybe composed of a plastic material with Abbe number V2=23.3.

Lens system 210 as specified in Tables 2A-2C is configured to correctoptical aberrations as described in reference to lens system 110 andTables 1A-1C. FIG. 4 illustrates a plot of the polychromatic rayaberration curves over the half field of view (HFOV=18 degrees), for anobject field point on-axis (at 0 degree) to an off-axis field point at18 degrees, and over the visible spectral band ranging from 470 nm to650 nm for a compact telephoto lens system 210 as illustrated in FIG. 3and described in Tables 2A-2C.

The optical prescriptions in Tables 2A-2C describes an exampleembodiment of a compact telephoto lens system 210 as illustrated in FIG.3 that includes five lens elements with refractive power and effectivefocal length f, and in which a second lens element L2 has negativerefractive power or negative focal length f2 and a concave object sidesurface. In addition, lens element L2 is biconcave in shape and has anegative radius of curvature R4 and a positive radius of curvature R5(i.e., R4<0, R5>0, and R4/R5<0).

In the example embodiment of lens system 210 as described by the opticalprescription in Tables 2A-2C, the refractive power distribution of thelens elements in terms of the focal lengths are f1=2.697 mm, f2=−4.446mm, f3=−12.466 mm, f4=−2.684 mm and f5=4.053 mm. Lens element L1 is abiconvex lens with R2/R3=−0.183. Lens elements L2, L3, and L4 arebiconcave in shape with radii of curvature R4/R5=−4.494, R6/R7=−0.606,and R8/R9=−1.20, respectively. Lens element L5 is biconvex in shape withR10/R11=−1.126. The aspheric coefficients for the surfaces of the lenselements in lens system 210 in the example embodiment are listed inTable 2C. Configuring lens system 210 according to the arrangement ofthe power distribution of the lens elements, and adjusting the radii ofcurvature and aspheric coefficients as shown in Tables 2A-2C, the totaltrack length (TTL) of the lens system 210 may be reduced (e.g., to 5.7mm as shown in Table 2A) and aberration of the system may effectively becorrected to obtain optical performance of high image quality resolutionin a small form factor telephoto camera 200.

FIG. 5 is a cross-sectional illustration of an example embodiment of acompact telephoto camera 300 including a compact telephoto lens system310. Lens system 310 includes five lens elements (301-305) withrefractive power. Arranged along an optical axis AX of the camera 300from an object side to an image side (from left to right in the drawing)are an aperture stop AS, a first lens element L1 (301) with positiverefractive power having a convex object side surface and focal lengthf1, a second lens element L2 (302) with negative refractive power havinga convex object side surface and focal length f2, a third lens elementL3 (303) with positive refractive power having a convex object sidesurface and focal length f3, a fourth lens element L4 (304) withnegative refractive power having a concave object side surface and focallength f4, and a fifth lens element L5 (305) with positive refractivepower having a convex image side surface and focal length f5. The lenssystem 310 forms an image plane at a surface of a photosensor 320. Insome embodiments, an infrared (IR) filter may be located between thefifth lens element L5 and the photosensor 320.

Effective focal length of the lens system 310 is given as f. The totaltrack length (TTL) of the compact telephoto lens system 110 is thedistance on the optical axis AX between the object side surface of thefirst lens element L1 and the image plane. The lens system 310 isconfigured such that the telephoto ratio (TTL/f) of the lens system 310satisfies the relation:

0.74<TTL/f<1.0.

An aperture stop AS, which may be located at the front surface of lenselement L1, determines the entrance pupil aperture of lens system 310.The lens system 310 focal ratio or f-number f# is defined as the lenssystem 310 effective focal length f divided by the entrance pupildiameter. The IR filter may act to block infrared radiation that coulddamage or adversely affect the photosensor, and may be configured so asto have no effect on f.

Tables 3A-3C provide example values for various optical and physicalparameters of an example embodiment of a camera 300 and lens system 310as illustrated in FIG. 5. Tables 3A-3C may be referred to as providingan optical prescription for the lens system 310.

Referring to Tables 3A-3C, embodiments of lens system 310 coverapplications in the visible region of the spectrum from 470 nm to 650 nmwith reference wavelength at 555 nm. The lens system 310 effective focallength f shown in Table 3A is the nominal value at 555 nm. The opticalprescription in Tables 3A-3C provides high image quality performance atf/2.8 over the 470 nm to 650 nm spectrum, for an effective focal lengthf of 7 mm, covering a field of view (FOV) of 36 degrees. The 7 mm focallength compact lens system 310, illustrated in FIG. 5 with an opticalprescription as shown in 3A-3C, has a total track length (TTL) of 5.6mm, and a telephoto ratio (TTL/f) of 0.80.

The five lens elements L1, L2, L3, L4, and L5 of lens system 310 may becomposed of plastic materials with refractive indices and Abbe numbersas listed in Table 3B. As shown in Table 3B, in at least someembodiments of lens system 310, two types of plastic materials may beused for the lens elements. Lens elements L1 and L4 may be composed ofthe same plastic material with an Abbe number V1=56.1, and lens elementsL2, L3, and L5 may be composed of another plastic material having anAbbe number V2=23.3.

Lens system 310 as specified in Tables 3A-3C is configured to correctoptical aberrations as described in reference to lens system 110 andTables 1A-1C. FIG. 6 illustrates a plot of the polychromatic rayaberration curves over the half field of view (HFOV) covering 0-18degrees, and over the visible spectral band ranging from 470 nm to 650nm for a compact telephoto lens system 310 as illustrated in FIG. 5 anddescribed in Tables 3A-3C.

The optical prescriptions in Tables 3A-3C describe an example embodimentof a compact telephoto lens system 310 as illustrated in FIG. 5 thatincludes five lens elements with refractive power and effective focallength f in which a second lens element L2 with negative refractivepower or negative focal length f2 has a convex object side surface and athird lens element L3 with positive refractive power or positive focallength f3 has a convex object side surface. In addition, in thisembodiment, lens element L2 is negative meniscus in shape and haspositive radii of curvature R4 and R5, with R4>R5 and R4/R5>1.0. Lenselement L3 is positive meniscus in shape and has positive radii ofcurvature R6 and R7, with R6<R7 and 0<R6/R7<1.0.

In the example embodiment of lens system 310 as described by the opticalprescription in Tables 3A-3C, the refractive power distribution of thelens elements in terms of the focal lengths are f1=2.762 mm, f2=−3.511mm, f3=82.286 mm, f4=−3.262 mm and f5=5.759 mm. Lens elements L1 and L5are both biconvex in shape with R2/R3=−0.206 and R10/R11=−0.148. Theshape of the negative meniscus lens element L2 has radii of curvatureR4/R5=3.15. Lens element L3 has positive refractive power and ispositive meniscus in shape with radii of curvature R6/R7=0.739. Lenselement L4 is biconcave in shape with radii of curvature R8/R9=−2.775.The aspheric coefficients for the surfaces of the compact imaging systemin lens system 310 in the example embodiment are listed in Table 3C.Configuring lens system 310 according to the arrangement of the powerdistribution of the lens elements, and adjusting the radii of curvatureand aspheric coefficients as shown in Tables 3A-3C, the total tracklength (TTL) of the lens system 310 may be reduced (e.g., to 5.6 mm asshown in Table 3A) and aberration of the system may effectively becorrected to obtain optical performance of high image quality resolutionin a small form factor telephoto camera 300.

FIG. 7 is a cross-sectional illustration of an example embodiment of acompact telephoto camera 400 including a compact telephoto lens system410 that includes four lens elements (401-404) with refractive power,rather than five lens elements as shown in FIGS. 1, 3, and 5. Arrangedalong an optical axis AX of the camera 400 from an object side to animage side (from left to right in the drawing) are an aperture stop AS,a first lens element L1 (401) with positive refractive power having aconvex object side surface and focal length f1, a second lens element L2(402) with negative refractive power and focal length f2, a third lenselement L3 (403) with negative refractive power and focal length f3, anda fourth lens element L4 (404) with positive refractive power and focallength f4. The lens system 410 forms an image plane at a surface of aphotosensor 420. In some embodiments, an infrared (IR) filter may belocated between the fourth lens element L4 and the photosensor 420.

Effective focal length of the lens system 410 is given as f. The totaltrack length (TTL) of the compact telephoto lens system 410 is thedistance on the optical axis AX between the object side surface of thefirst lens element L1 and the image plane. The lens system 410 isconfigured such that the telephoto ratio (TTL/f) of the lens system 410satisfies the relation:

0.74<TTL/f<1.0.

An aperture stop AS, which may be located at the front surface of lenselement L1, determines the entrance pupil aperture of lens system 410.The lens system 410 focal ratio or f-number f# is defined as the lenssystem 410 effective focal length f divided by the entrance pupildiameter. The IR filter may act to block infrared radiation that coulddamage or adversely affect the photosensor, and may be configured so asto have no effect on f.

Tables 4A-4C provide example values for various optical and physicalparameters of an example embodiment of a camera 400 and lens system 410as illustrated in FIG. 7. Tables 4A-4C may be referred to as providingan optical prescription for the lens system 410.

Referring to Tables 4A-4C, embodiments of lens system 410 coverapplications in the visible region of the spectrum from 470 nm to 650 nmwith reference wavelength at 555 nm. The 7-mm effective focal length fshown in Table 4A is the nominal value at 555 nm. The opticalprescriptions in Tables 4A-4C provide high image quality performance atf/2.8 over the 470 nm to 650 nm spectrum, for a lens system 410 coveringa field of view (FOV) of 36 degrees. The compact lens system 410,illustrated in FIG. 7 and with optical prescription as shown in Tables4A-4C, has a total track length (TTL) of 5.7 mm, and a telephoto ratio(TTL/f) of 0.814.

The four lens elements L1, L2, L3, and L4 of lens system 410 may becomposed of plastic materials with refractive indices and Abbe numbersas listed in Table 4B. As shown in Table 4B, in at least someembodiments, two types of plastic materials may be used for the lenselements. Lens elements L1 and L3 may be composed of the same plasticmaterial with an Abbe number V1=56.1, and lens elements L2 and L4 may becomposed of another plastic material with an Abbe number V2=23.3.

Lens system 410 as specified in Tables 4A-4C is configured to correctoptical aberrations as described in reference to lens system 110 andTables 1A-1C. FIG. 8 illustrates a plot of the polychromatic rayaberrations curves over the half field of view (HFOV) covering 0-18degrees, and over the visible spectral band ranging from 470 nm to 650nm for a compact telephoto lens system 410 as illustrated in FIG. 7 anddescribed in Tables 4A-4C.

The optical prescriptions in Tables 4A-4C describe an example embodimentof a compact telephoto lens system 410 as illustrated in FIG. 7 thatincludes four lens elements with refractive power and effective focallength f in which a second lens element L2 with negative refractivepower or negative focal length f2 has a convex object side surface, athird lens element L3 with negative refractive power or negative focallength f3 has a concave object side surface, and a fourth lens elementL4 with positive power or positive focal length f4 has a convex objectside surface. In addition, in a particular embodiment, lens element L1is biconvex in shape, and lens element L2 is negative meniscus in shapeand has positive radii of curvature R4 and R5 where R4>R5, andR4/R5>1.0. Lens element L3 is biconcave in shape, and lens element L4 ispositive meniscus in shape and has positive radii of curvature R8 andR9, wherein R8<R9, and 0<R8/R9<1.0.

In the example embodiment of lens system 410 as described by the opticalprescription in Tables 4A-4C, the refractive power distribution of thelens elements in terms of the focal lengths are f1=2.911 mm, f2=−4.152mm, f3=−4.4093 mm, and f4=7.287 mm. Lens elements L1 and L2 are spacedclosely such that the combination of L1 and L2 may be considered anair-spaced doublet lens of positive refractive power or positive focallength f12. Lens elements L3 and L4 are also spaced closely such thatthe combination of L3 and L4 may be considered a doublet lens havingnegative refractive power and negative focal length f34. In the exampleembodiment of lens system 410 as described by the optical prescriptionin Tables 4A-4C, f12=5.80 mm, and f34=−8.87 mm, and the two air-spaceddoublets are separated by an axial distance of T5=2.3327 mm. Lenselement L1 is biconvex in shape with radii of curvature R2/R3=−0.196.Negative meniscus lens element L2 has radii of curvature R4/R5=2.726.With such arrangement of radii of curvature, the combination of L1 andL2 is an air-spaced doublet of the Gaussian type. Lens element L3 isbiconcave in shape with radii of curvature R6/R7=−314.045. Lens elementL4 has radii of curvature R8/R9=0.479. The aspheric coefficients for thesurfaces of the lens elements in this example embodiment of lens system410 are listed in Table 4C. Configuring lens system 410 according to thearrangement of the power distribution of the lens elements, andadjusting the radii of curvature and aspheric coefficients as shown inTables 4A-4C, the total track length (TTL) of the lens system 410 may bereduced (e.g., to 5.7 mm as shown in Table 4A) and aberration of thesystem may effectively be corrected to obtain optical performance ofhigh image quality resolution in a small form factor telephoto camera400.

Tables 5A-5C provide example values for various optical and physicalparameters of an alternative example embodiment of a camera 400 and lenssystem 410 as illustrated in FIG. 7. Tables 5A-5C may be referred to asproviding an alternative optical prescription for the lens system 410.

Referring to Tables 5A-5C, an embodiment of a compact telephoto lenssystem 410 with four lens elements as illustrated in FIG. 7 is describedwith 7 mm effective focal length f, f/2.6, 36 degrees FOV, 5.85 mm TTL,and TTL/f=0.836. The optical prescription in Tables 5A-5C describes anembodiment of lens system 410 in which the lens elements with negativepowers and focal lengths, L2 and L3, both have a convex object surface.In this particular embodiment, L2 and L3 are both negative menisci inshape in the vicinity of the optical axis AX. The lens element L3 haspositive radii of curvature R6 and R7, where R6>R7 and R6/R7>1.0. FIG. 9illustrates a plot of the polychromatic ray aberrations curves over thehalf field of view (HFOV) covering 0-18 degrees, and over the visiblespectral band ranging from 470 nm to 650 nm for a compact telephoto lenssystem 410 as illustrated in FIG. 7 and described in Tables 5A-5C.

The optical prescriptions in Tables 5A-5C describe an example embodimentof a compact telephoto lens system 410 as illustrated in FIG. 7 thatincludes four lens elements with refractive power and effective focallength f, in which the refractive power distribution of the lenselements L1, L2, L3, and L4 in terms of the focal lengths are f1=2.936mm, f2=−4.025 mm, f3=−4.101 mm, and f4=6.798 mm. Lens elements L1 and L2are spaced closely such that the combination of L1 and L2 may beconsidered an air-spaced doublet lens of positive refractive power orpositive focal length f12. Lens elements L3 and L4 are also spacedclosely such that the combination of L3 and L4 may be considered adoublet lens having negative refractive power and negative focal lengthof f34. In the example embodiment of lens system 410 as described by theoptical prescription in Tables 5A-5C, f12=5.922 mm, and f34=−9.70 mm,and the two air-spaced doublets are separated by an axial distance ofT5=2.2376 mm. Lens element L1 is biconvex in shape with R2/R3=−0.225.Negative meniscus lens element L2 has radii of curvature R4/R5=3.782.With such arrangement of radii of curvature, the combination of L1 andL2 is an air-spaced doublet of the Gaussian type. Lens element L3 isnegative meniscus in shape with radii of curvature R6/R7=15.625. Lenselement L4 has vertex radii of curvature R8/R9=0.462. The asphericcoefficients for the surfaces of the lens elements in this exampleembodiment of lens system 410 are listed in Table 5C. Configuring lenssystem 410 according to the arrangement of the power distribution of thelens elements, and adjusting the radii of curvature and asphericcoefficients as shown in Tables 5A-5C, the total track length (TTL) ofthe lens system 410 may be reduced (e.g., to 5.85 mm as shown in Table5A) and aberration of the system may effectively be corrected to obtainoptical performance of high image quality resolution in a small formfactor telephoto camera 400.

Tables 6A-6C provide example values for various optical and physicalparameters of another alternative example embodiment of a camera 400 andlens system 410 as illustrated in FIG. 7. Tables 6A-6C may be referredto as providing another alternative optical prescription for the lenssystem 410.

Referring to Tables 6A-6C, an embodiment of a compact telephoto lenssystem 410 with four lens elements as illustrated in FIG. 7 is describedwith 7-mm effective focal length f, f/2.5, 36 degrees FOV, 5.9 mm TTL,and telephoto ratio (TTL/f) of 0.842. The optical prescription in Tables6A-6C describes an embodiment of lens system 410 in which positive lenselement L1 is biconvex in shape, negative lens elements L2 and L3 bothhave a convex object side surface and are menisci in shape, and positivelens element L4 has a convex object side surface and is positivemeniscus in shape. FIG. 10 illustrates a plot of the polychromatic rayaberrations curves over the half field of view HFOV covering 0-18degrees, and over the visible spectral band ranging from 470 nm to 650nm for a compact telephoto lens system 410 as illustrated in FIG. 7 anddescribed in Tables 6A-6C.

The optical prescriptions in Tables 6A-6C describe an example embodimentof a compact telephoto lens system 410 as illustrated in FIG. 7 thatincludes four lens elements with refractive power and effective focallength f, in which the refractive power distribution of the lenselements L1, L2, L3, and L4 in terms of focal length are f1=2.932 mm,f2=−3.872 mm, f3=−4.250 mm, and f4=6.668 mm. Lens elements L1 and L2 arespaced closely such that the combination of L1 and L2 may be consideredan air-spaced doublet lens of positive refractive power or positivefocal length f12. Lens elements L3 and L4 are also spaced closely suchthat the combination of L3 and L4 may be considered a doublet lenshaving negative refractive power and negative focal length f34. In theexample embodiment of lens system 410 as described by the opticalprescription in Tables 6A-6C, f12=6.063 mm, f34=−10.744 mm, and the twoair-spaced doublets are separated by an axial distance of T5=2.2096 mm.Lens element L1 is biconvex in shape with radii of curvatureR2/R3=−0.258, and the negative meniscus lens element L2 has radii ofcurvature R4/R5=3.936. With such arrangement of radii of curvature, thecombination of L1 and L2 is an air-spaced doublet of the Gaussian type.In the example embodiment of lens system 410 as described by the opticalprescription in Tables 6A-6C, lens element L3 is negative meniscus inshape with radii of curvature R6/R7=5.750. Lens element L4 has vertexradii of curvature with R8/R9=0.470. The aspheric coefficients for thesurfaces of the lens elements in this example embodiment of lens system410 are listed in Table 6C. Configuring lens system 410 according to thearrangement of the power distribution of the lens elements, andadjusting the radii of curvature and aspheric coefficients as shown inTables 5A-5C, the total track length (TTL) of the lens system 410 may bereduced (e.g., to 5.9 mm as shown in Table 6A) and aberration of thesystem may effectively be corrected to obtain optical performance ofhigh image quality resolution in a small form factor telephoto camera400.

FIG. 11 is a cross-sectional illustration of an example embodiment of acompact telephoto camera 500 including a compact telephoto lens system510. Lens system 510 includes five lens elements (501-505) withrefractive power. Lens system 510 may be viewed as a variation of lenssystems 110 or 210 of FIGS. 1 and 3 or of lens system 310 of FIG. 5, andelements of the lens systems may be similar. However, in lens system510, the aperture stop is located at the first lens element 501 andbehind the front vertex of the lens system 510, rather than at or infront of the front vertex of the lens systems as illustrated in FIGS. 1,3, and 5.

Tables 7A-7C provide example values for various optical and physicalparameters of an example embodiment of a camera 500 and lens system 510as illustrated in FIG. 11. Tables 7A-7C may be referred to as providingan optical prescription for the lens system 510. The opticalprescription in Tables 7A-7C is for a lens system 510 with an effectivefocal length f of 7 mm at 555 nm wavelength, a focal ratio of f/2.8,with 36 degrees FOV, TTL of 6.0 mm, and with TTL/f equal to 0.857. Lenssystem 510 is a compact imaging lens system designed for the visiblespectrum covering 470 nm to 650 nm.

The lens elements L1, L2, L3, L4, and L5 of lens system 510 may becomposed of plastic materials with refractive indices and Abbe numbersas listed in Table 7B. Referring to lens system 510, the lens elementsL1 and L4 may be composed of a plastic material having an Abbe number ofV1=56.1. The lens elements L2, L3, and L5 may be composed of a plasticmaterial with Abbe number V2=23.3.

Lens system 510 as specified in Tables 7A-7C is configured to correctoptical aberrations as described in reference to lens system 110 andTables 1A-1C. FIG. 12 illustrates a plot of the polychromatic rayaberration curves over the half field of view (HFOV=18 degrees), for anobject field point on-axis (at 0 degree) to an off-axis field point at18 degrees, and over the visible spectral band ranging from 470 nm to650 nm for a compact telephoto lens system 510 as illustrated in FIG. 11and described in Tables 7A-7C.

The aspheric coefficients for the surfaces of the lens elements in lenssystem 510 in the example embodiment are listed in Table 7C. Configuringlens system 510 according to the arrangement of the power distributionof the lens elements, and adjusting the radii of curvature and asphericcoefficients as shown in Tables 7A-7C, the total track length (TTL) ofthe lens system 510 may be reduced (e.g., to 6.0 mm as shown in Table7A) and aberration of the system may effectively be corrected to obtainoptical performance of high image quality resolution in a small formfactor telephoto camera 500.

FIG. 13 is a cross-sectional illustration of an example embodiment of acompact telephoto camera 600 including a compact telephoto lens system610. Lens system 610 includes five lens elements (601-605) withrefractive power. Lens system 610 may be viewed as a variation of lenssystems 110, 210, or 310 of FIGS. 1, 3, and 5, respectively, or of lenssystem 510 of FIG. 11, and elements of the lens systems may be similar.However, in lens system 610, the aperture stop is located between thefirst and second lens elements 601 and 602 of the lens system 610,rather than at or in front of the first lens element as illustrated inFIGS. 1, 3, 5, and 11.

Tables 8A-8C provide example values for various optical and physicalparameters of an example embodiment of a camera 600 and lens system 610as illustrated in FIG. 13. Tables 8A-8C may be referred to as providingan optical prescription for the lens system 610. The opticalprescription in Tables 8A-8C is for a lens system 610 with an effectivefocal length f of 7 mm at 555 nm wavelength, a focal ratio of f/2.8,with 36 degrees FOV, TTL of 6.0 mm, and with TTL/f equal to 0.857. Lenssystem 610 is a compact imaging lens system designed for the visiblespectrum covering 470 nm to 650 nm.

The lens elements L1, L2, L3, L4, and L5 of lens system 610 may becomposed of plastic materials with refractive indices and Abbe numbersas listed in Table 8B. Referring to lens system 610, the lens elementsL1 and L4 may be composed of a plastic material having an Abbe number ofV1=56.1. The lens elements L2, L3, and L5 may be composed of a plasticmaterial with Abbe number V2=23.3.

Lens system 610 as specified in Tables 8A-8C is configured to correctoptical aberrations as described in reference to lens system 110 andTables 1A-1C. FIG. 14 illustrates a plot of the polychromatic rayaberration curves over the half field of view (HFOV=18 degrees), for anobject field point on-axis (at 0 degree) to an off-axis field point at18 degrees, and over the visible spectral band ranging from 470 nm to650 nm for a compact telephoto lens system 610 as illustrated in FIG. 13and described in Tables 8A-8C.

The aspheric coefficients for the surfaces of the lens elements in lenssystem 610 in the example embodiment are listed in Table 8C. Configuringlens system 610 according to the arrangement of the power distributionof the lens elements, and adjusting the radii of curvature and asphericcoefficients as shown in Tables 8A-8C, the total track length (TTL) ofthe lens system 610 may be reduced (e.g., to 6.0 mm as shown in Table8A) and aberration of the system may effectively be corrected to obtainoptical performance of high image quality resolution in a small formfactor telephoto camera 600.

FIG. 15 is a high-level flowchart of a method for capturing images usinga camera with a telephoto lens system that includes five lens elementsas illustrated in FIGS. 1, 3, 5, 11, and 13, according to at least someembodiments. As indicated at 1100, light from an object field in frontof the camera is received at a first lens element of the camera throughan aperture stop. In some embodiments, the aperture stop may be locatedat the front vertex of the lens system, or between the front vertex andthe object plane, as illustrated in FIGS. 1, 3, and 5. Alternatively,the aperture stop may be located behind the front vertex of the lenssystem as illustrated in FIGS. 11 and 13, for example at the first lenselement as shown in FIG. 11, or between the first and second lenselements as shown in FIG. 13. As indicated at 1102, the first lenselement refracts the light to a second lens element. As indicated at1104, the light is then refracted by the second lens element to a thirdlens element. As indicated at 1106, the light is then refracted by thethird lens element to a fourth lens element. As indicated at 1108, thelight is then refracted by the fourth lens element to a fifth lenselement. As indicated at 1110, the light is refracted by the fifth lenselement to form an image at an image plane at or near the surface of aphotosensor. As indicated at 1112, the image is captured by thephotosensor. While not shown, in some embodiments, the light may passthrough an infrared filter that may for example be located between thefifth lens element and the photosensor.

In some embodiments, the five lens elements may be configured asillustrated in FIG. 1 and according to the optical prescription providedin Tables 1A-1C. Alternatively, the five lens elements may be configuredas illustrated in FIG. 3 and according to the optical prescriptionprovided in Tables 2A-2C. As yet another alternative, the five lenselements may be configured as illustrated in FIG. 5 and according to theoptical prescription provided in Tables 3A-3C. As yet anotheralternative, the five lens elements may be configured as illustrated inFIG. 11 and according to the optical prescription provided in Tables7A-7C. As yet another alternative, the five lens elements may beconfigured as illustrated in FIG. 13 and according to the opticalprescription provided in Tables 8A-8C. However, note that variations onthe examples given in Tables 1A-1C, 2A-2C, 3A-3C, 7A-7C, and 8A-8C arepossible while achieving similar optical results.

FIG. 16 is a flowchart of a method for capturing images using a camerawith a telephoto lens system that includes four lens elements asillustrated in FIG. 7, according to at least some embodiments. Asindicated at 1200, light from an object field in front of the camera isreceived at a first lens element of the camera through an aperture stop.While FIG. 7 shows the aperture stop located at the front vertex of thelens system, in some embodiments location of the aperture stop may becloser to or farther away from the first lens element. Further, in someembodiments, the aperture stop may be located elsewhere in the telephotolens system. As just one example, the aperture stop may be locatedbetween the first and second lens elements.

As indicated at 1202, the first lens element refracts the light to asecond lens element. As indicated at 1204, the light is then refractedby the second lens element to a third lens element. As indicated at1206, the light is then refracted by the third lens element to a fourthlens element. As indicated at 1208, the light is refracted by the fourthlens element to form an image at an image plane at or near the surfaceof a photosensor. As indicated at 1210, the image is captured by thephotosensor. While not shown, in some embodiments, the light may passthrough an infrared filter that may for example be located between thefourth lens element and the photosensor.

In some embodiments, the four lens elements may be configured asillustrated in FIG. 7 and according to the optical prescription providedin Tables 4A-4C. Alternatively, the four lens elements may be configuredas illustrated in FIG. 7 and according to the optical prescriptionprovided in Tables 5A-5C. As yet another alternative, the four lenselements may be configured as illustrated in FIG. 7 and according to theoptical prescription provided in Tables 6A-6C. However, note thatvariations on the examples given in Tables 4A-4C, 5A-5C, and 6A-6C arepossible while achieving similar optical results.

Example Lens System Tables

The following Tables provide example values for various optical andphysical parameters of example embodiments of the telephoto lens systemsand cameras as described herein in reference to FIGS. 1 through 14.Tables 1A-1C correspond to an example embodiment of a lens system 110with five lens elements as illustrated in FIG. 1. Tables 2A-2Ccorrespond to an example embodiment of a lens system 210 with five lenselements as illustrated in FIG. 3. Tables 3A-3C correspond to an exampleembodiment of a lens system 310 with five lens elements as illustratedin FIG. 5. Tables 4A-4C, 5A-5C, and 6A-6C correspond to three differentexample embodiments of a lens system 410 with four lens elements asillustrated in FIG. 7. Tables 7A-7C correspond to an example embodimentof a lens system 510 with five lens elements as illustrated in FIG. 11.Tables 8A-8C correspond to an example embodiment of a lens system 510with five lens elements as illustrated in FIG. 13.

In the Tables, all dimensions are in millimeters unless otherwisespecified. “S#” stands for surface number. A positive radius indicatesthat the center of curvature is to the right of the surface. A negativeradius indicates that the center of curvature is to the left of thesurface. “INF” stands for infinity (as used in optics). “ASP” indicatesan aspheric surface, and “FLAT” indicates a flat surface. The thickness(or separation) is the axial distance to the next surface. The designwavelengths represent wavelengths in the spectral band of the imagingoptical system.

For the materials of the lens elements and IR filter, a refractive indexN_(d) at the helium d-line wavelength is provided, as well as an Abbenumber V_(d) relative to the d-line and the C- and F-lines of hydrogen.The Abbe number, V_(d), may be defined by the equation:

V _(d)=(N _(d)−1)/(N _(F) −N _(C)),

where N_(F) and N_(C) are the refractive index values of the material atthe F and C lines of hydrogen, respectively.

Referring to the Tables of aspheric constants (Tables, 1C, 2C, 3C, 4C,5C, 6C, 7C, and 8C), the aspheric equation describing an asphericalsurface may be given by:

$Z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {\left( {1 + K} \right)c^{2}r^{2}}}} + {Ar}^{4} + {Br}^{6} + {Cr}^{8} + {Dr}^{10} + {Er}^{12} + {FR}^{14} + {GR}^{16} + {Hr}^{18} + \ldots}$

where Z is the sag of surface parallel to the z-axis (the z-axis and theoptical axis (AX) are coincident in these example embodiments), r is theradial distance from the vertex, c is the curvature of the surface atthe vertex (the reciprocal of the radius of curvature of the surface), Kis the conic constant, and A, B, C, D, E, F, G, and H are the asphericcoefficients. In the Tables, “E” denotes the exponential notation(powers of 10).

Note that the values given in the following Tables for the variousparameters in the various embodiments of the telephoto lens system aregiven by way of example and are not intended to be limiting. Forexample, one or more of the parameters for one or more of the surfacesof one or more of the lens elements in the example embodiments, as wellas parameters for the materials of which the elements are composed, maybe given different values while still providing similar performance forthe lens system. In particular, note that some values in the Tables maybe scaled up or down for larger or smaller implementations of a camerausing an embodiment of a telephoto lens system as described herein.

Further note that surface numbers (S#) of the elements in the variousembodiments of the telephoto lens system as shown in the Tables arelisted from a first surface 0 at the object plane to a last surface atthe image plane. Since number and location of elements may vary inembodiments, the surface number(s) that correspond to some elements mayvary in the different Tables. For example, in the first six sets ofTables, the aperture stop is surface 1, and the first lens element (L1)has surfaces 2 and 3. However, in Tables 7A-7C and 8A-8C, the locationof the aperture stop is different, and thus the surface numbers aredifferent in the Tables. For example, in Tables 7B and 7C, the firstlens element (L1) has surfaces 4 and 5, and in Tables 8A and 8B thefirst lens element (L1) has surfaces 1 and 2 (while the aperture stop issurface 3). In particular, note that where reference is given to theradius of curvature (R#) of the surfaces of the lens elements (L#) inthis document, the reference (R#) used (e.g., R2 and R3 for the surfacesof lens element L1) are the same for all of the example embodiments, andmay but do not necessarily correspond to the surface numbers of the lenselements as given in the Tables.

TABLE 1A Focal length (f) 7.0 mm F-Number 2.8 Half FOV 18° Total tracklength (TTL) 5.7 mm Telephoto ratio (TTL/f) 0.814 Design wavelengths 650nm, 610 nm, 555 nm, 510 nm, 470 nm

TABLE 1B Refractive Abbe Surface Radius Thickness or Index NumberElement (S#) R Shape Separation Material N_(d) V_(d) Object plane 0 INFFLAT INF Aperture 1 INF FLAT 0.0 stop L1 2 1.673 ASP 1.1684 Plastic1.544 56.1 3 −9.726 ASP 0.1000 L2 4 11.643 ASP 0.2300 Plastic 1.632 23.35 2.017 ASP 0.7077 L3 6 −213.666 ASP 0.2300 Plastic 1.632 23.3 7 14.671ASP 1.3137 L4 8 −4.521 ASP 0.2300 Plastic 1.544 56.1 9 2.864 ASP 0.1000L5 10 4.893 ASP 0.7763 Plastic 1.632 23.3 11 −8.103 ASP 0.3039 IR filter12 INF FLAT 0.2300 Glass 1.516 64.1 13 INF FLAT 0.3099 Image plane 14INF FLAT

TABLE 1C ASPHERIC CONSTANTS Curvature A B C D S# (c) K E F G H 20.59785079 −0.19216064  1.61976E−02 −2.16719E−02  1.43453E−028.88075E−04 −3.00338E−03 0.00000E+00 0.00000E+00 0.00000E+00 3−0.10282157 0.00000000  3.33438E−02 −1.89863E−02  −2.81318E−02 1.75534E−02 −2.74116E−03 −2.31821E−04  0.00000E+00 0.00000E+00 40.08589051 0.00000000 −4.31287E−02 2.99609E−02 1.71198E−03 −9.94839E−03  6.40409E−03 0.00000E+00 0.00000E+00 0.00000E+00 5 0.49577936−25.0000000  1.97722E−01 −2.33942E−01  3.37138E−01 −1.85937E−01  1.00492E−01 0.00000E+00 0.00000E+00 0.00000E+00 6 −0.468020E−020.00000000  6.09888E−02 −2.76429E−02  1.05749E−01 −4.61969E−02  0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 7 0.06816110 0.00000000 1.02750E−01 1.70897E−02 1.88497E−02 3.44798E−02 −3.06636E−020.00000E+00 0.00000E+00 0.00000E+00 8 −0.22118912 −2.16463818−7.34172E−02 3.07556E−03 5.70157E−03 2.85101E−04 −9.26309E−040.00000E+00 0.00000E+00 0.00000E+00 9 0.34921854 0.00000000 −7.41657E−021.37581E−02 −3.86267E−03  3.22109E−04 −6.96384E−05 0.00000E+000.00000E+00 0.00000E+00 10 0.20438810 0.00000000 −1.68054E−022.75927E−03 −1.69414E−04  9.69418E−05  0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 11 −0.12341260 0.00000000 −3.33203E−025.74025E−03 1.31067E−03 −1.14529E−04   0.00000E+00 0.00000E+000.00000E+00 0.00000E+00

TABLE 2A Focal length (f) 7.0 mm F-Number 2.8 Half FOV 18° Total tracklength (TTL) 5.7 mm Telephoto ratio (TTL/f) 0.814 Design wavelengths 650nm, 610 nm, 555 nm, 510 nm, 470 nm

TABLE 2B Refractive Abbe Surface Radius Thickness or Index NumberElement (S#) R Shape Separation Material N_(d) V_(d) Object plane 0 INFFLAT INF Aperture 1 INF FLAT 0.0 stop L1 2 1.679 ASP 1.1080 Plastic1.544 56.1 3 −9.162 ASP 0.1000 L2 4 −15.649 ASP 0.2300 Plastic 1.63223.3 5 3.482 ASP 1.1305 L3 6 −12.801 ASP 0.2300 Plastic 1.632 23.3 721.119 ASP 1.0559 L4 8 −3.266 ASP 0.2300 Plastic 1.544 56.1 9 2.724 ASP0.1000 L5 10 5.272 ASP 1.0356 Plastic 1.632 23.3 11 −4.681 ASP 0.1337 IRfilter 12 INF FLAT 0.2100 Glass 1.516 64.1 13 INF FLAT 0.1363 Imageplane 14 INF FLAT

TABLE 2C ASPHERIC CONSTANTS Curvature A B C D S# (c) K E F G H 20.59554801 0.22669364 9.80281E−03 −3.81227E−02  2.39681E−02−6.29128E−03  −2.75496E−03  −2.69638E−04  0.00000E+00 0.00000E+00 3−0.10914948 0.00000000 3.73187E−02 −8.91760E−03  −5.89384E−02 4.41115E−02 −1.26858E−02  1.16125E−03 0.00000E+00 0.00000E+00 4−0.06390120 0.00000000 6.93172E−02 −4.31157E−02  2.33346E−02−2.33074E−02  2.22119E−02 −4.84076E−03  0.00000E+00 0.00000E+00 50.28715632 8.70133393 5.21579E−03 7.15829E−02 −4.60926E−02  1.24310E−023.32216E−02 0.00000E+00 0.00000E+00 0.00000E+00 6 −0.07812160 0.000000003.96000E−02 −3.42179E−02  7.75523E−02 −4.22361E−02  0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 7 0.04735179 0.00000000 1.01117E−01−3.21118E−02  9.03668E−02 −3.37156E−02  −6.52751E−03  0.00000E+000.00000E+00 0.00000E+00 8 −0.30620054 0.85965815 −4.91398E−02 −5.57533E−03  1.31557E−02 1.22280E−03 −9.54019E−04  −2.40349E−06 0.00000E+00 0.00000E+00 9 0.36712935 0.00000000 −8.88955E−02 2.87927E−02 −8.83436E−03  1.57329E−03 −2.24134E−04  0.00000E+000.00000E+00 0.00000E+00 10 0.18967188 0.00000000 −2.38313E−02 5.50321E−03 −9.19080E−04  −9.80631E−05  0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 11 −0.21364516 3.15790955 −3.17139E−02 3.80781E−03 3.43810E−04 −3.27888E−05  0.00000E+00 0.00000E+000.00000E+00 0.00000E+00

TABLE 3A Focal length (f) 7.0 mm F-Number 2.8 Half FOV 18° Total tracklength (TTL) 5.6 mm Telephoto ratio (TTL/f) 0.80 Design wavelengths 650nm, 610 nm, 555 nm, 510 nm, 470 nm

TABLE 3B Refractive Abbe Surface Radius Thickness or Index NumberElement (S#) R Shape Separation Material N_(d) V_(d) Object plane 0 INFFLAT INF Aperture 1 INF FLAT 0.0 stop L1 2 1.753 ASP 1.0982 Plastic1.544 56.1 3 −8.514 ASP 0.1000 L2 4 4.680 ASP 0.2300 Plastic 1.632 23.35 1.485 ASP 0.4931 L3 6 13.930 ASP 0.2300 Plastic 1.632 23.3 7 18.844ASP 1.6356 L4 8 −6.782 ASP 0.2300 Plastic 1.544 56.1 9 2.444 ASP 0.1022L5 10 4.187 ASP 0.6076 Plastic 1.632 23.3 11 −28.195 ASP 0.3128 IRfilter 12 INF FLAT 0.2300 Glass 1.516 64.1 13 INF FLAT 0.3305 Imageplane 14 INF FLAT

TABLE 3C ASPHERIC CONSTANTS Curvature A B C D S# (c) K E F G H 20.57056992 −0.22528756  1.55892E−02 −2.22235E−02  1.79035E−02−4.66476E−03  −2.19158E−03 0.00000E+00 0.00000E+00 0.00000E+00 3−0.11744864 0.00000000  3.83035E−02 −2.70838E−02  −2.45562E−02 1.76178E−02 −3.16638E−03 −1.95794E−04  0.00000E+00 0.00000E+00 40.21369557 0.00000000 −1.22882E−01 5.09701E−02 7.09580E−04 −3.25926E−03  2.46121E−03 0.00000E+00 0.00000E+00 0.00000E+00 5 0.67325190−15.89218045  2.22697E−01 −3.89684E−01  4.24593E−01 −1.05738E−01 −3.50614E−03 −3.50614E−03  0.00000E+00 0.00000E+00 6 0.071785700.00000000  1.16266E−01 −6.77454E−02  1.28407E−01 −4.67691E−02  0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 7 0.05306826 0.00000000 1.29004E−01 3.48321E−02 −3.15339E−02  6.44071E−02 −2.93397E−020.00000E+00 0.00000E+00 0.00000E+00 8 −0.14745721 21.59367712−9.87056E−02 5.58192E−03 5.07171E−04 6.68101E−03 −4.75908E−03−3.45779E−04  0.00000E+00 0.00000E+00 9 0.40922164 0.00000000−1.05904E−01 1.45986E−02 −1.66551E−03  −1.34325E−03   1.31582E−040.00000E+00 0.00000E+00 0.00000E+00 10 0.23881840 0.00000000−3.24170E−02 7.53655E−03 9.20005E−04 −1.50434E−04  −3.32353E−060.00000E+00 0.00000E+00 0.00000E+00 11 −0.03546731 0.00000000−4.65887E−02 1.18976E−02 3.37895E−03 −6.21374E−04  −2.88832E−060.00000E+00 0.00000E+00 0.00000E+00

TABLE 4A Focal length (f) 7.0 mm F-Number 2.8 Half FOV 18° Total tracklength (TTL) 5.7 mm Telephoto ratio (TTL/f) 0.814 Design wavelengths 650nm, 610 nm, 555 nm, 510 nm, 470 nm

TABLE 4B Refractive Abbe Surface Radius Thickness or Index NumberElement (S#) R Shape Separation Material N_(d) V_(d) Object plane 0 INFFLAT INF Aperture 1 INF FLAT 0.0 stop L1 2 1.840 ASP 1.0077 Plastic1.544 56.1 3 −9.400 ASP 0.0500 L2 4 4.424 ASP 0.2300 Plastic 1.632 23.35 1.623 ASP 2.3327 L3 6 −703.898 ASP 0.2300 Plastic 1.544 56.1 7 2.241ASP 0.1400 L4 8 2.616 ASP 0.5932 Plastic 1.632 23.3 9 5.456 ASP 0.1000IR filter 10 INF FLAT 0.2300 Glass 1.516 64.1 11 INF FLAT 0.7864 Imageplane 12 INF FLAT

TABLE 4C ASPHERIC CONSTANTS Curvature A B C D S# (c) K E F G H 20.54359594 0.30403777  1.07464E−02 −3.61839E−02  3.17224E−02−1.52447E−02   1.71611E−03 0.00000E+00 0.00000E+00 0.00000E+00 3−0.10638305 0.00000000  1.04200E−02 −3.67175E−03  −8.29009E−03 7.47494E−03 −4.05255E−03 1.04543E−03 0.00000E+00 0.00000E+00 40.22603041 0.00000000 −1.20608E−01 9.40721E−02 −4.98486E−02  1.63431E−02−4.31776E−04 0.00000E+00 0.00000E+00 0.00000E+00 5 0.61621243−19.99986045  2.54494E−01 −3.83521E−01  3.88992E−01 −1.43164E−01 −2.41997E−02 2.78930E−02 0.00000E+00 0.00000E+00 6 −0.142066E−020.00000000 −1.51091E−01 −3.27080E−03  1.16418E−02 −1.05737E−02  3.37968E−03 −4.38034E−05  0.00000E+00 0.00000E+00 7 0.446150660.00000000 −1.42513E−01 2.41934E−02 −2.23618E−03  2.26565E−04 5.49855E−05 0.00000E+00 0.00000E+00 0.00000E+00 8 0.3823203 0.00000000−6.70140E−02 1.58234E−02 −2.93990E−03  2.26565E−04  0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 9 0.18327855 0.00000000 −7.53143E−022.30066E−02 −4.31351E−03  3.00055E−04  0.00000E+00 0.00000E+000.00000E+00 0.00000E+00

TABLE 5A Focal length (f) 7.0 mm F-Number 2.8 Half FOV 18° Total tracklength (TTL) 5.85 mm Telephoto ratio (TTL/f) 0.836 Design wavelengths650 nm, 610 nm, 555 nm, 510 nm, 470 nm

TABLE 5B Refractive Abbe Surface Radius Thickness or Index NumberElement (S#) R Shape Separation Material N_(d) V_(d) Object plane 0 INFFLAT INF Aperture 1 INF FLAT 0.0 stop L1 2 1.883 ASP 1.2034 Plastic1.544 56.1 3 −8.352 ASP 0.0500 L2 4 7.016 ASP 0.2300 Plastic 1.632 23.35 1.855 ASP 2.2376 L3 6 32.654 ASP 0.2300 Plastic 1.544 56.1 7 2.090 ASP0.1302 L4 8 2.520 ASP 0.6123 Plastic 1.632 23.3 9 5.452 ASP 0.2220 IRfilter 10 INF FLAT 0.2300 Glass 1.516 64.1 11 INF FLAT 0.7046 Imageplane 12 INF FLAT

TABLE 5C ASPHERIC CONSTANTS Curvature A B C D S# (c) K E F G H 20.53117357 0.10076738  1.25802E−02 −2.72609E−02  2.34732E−02−1.01134E−02   1.34365E−03 0.00000E+00 0.00000E+00 0.00000E+00 3−0.11972891 0.00000000  1.47086E−02 −4.24121E−03  −6.59940E−03 5.26728E−03 −1.93094E−03 4.11413E−04 0.00000E+00 0.00000E+00 40.14253186 0.00000000 −9.51041E−02 7.47540E−02 −4.03277E−02  1.40799E−02−1.19814E−03 0.00000E+00 0.00000E+00 0.00000E+00 5 0.53902729−24.72392792  2.18622E−01 −3.17371E−01  3.26704E−01 −1.34030E−01 −4.27313E−03 1.75696E−02 0.00000E+00 0.00000E+00 6 0.03062376 0.00000000−1.47113E−01 −9.39484E−04  1.10834E−02 −1.07303E−02   4.34759E−03−3.18692E−04  0.00000E+00 0.00000E+00 7 0.47851018 0.00000000−1.49733E−01 2.63283E−02 −3.05293E−03  6.55204E−05  7.10178E−050.00000E+00 0.00000E+00 0.00000E+00 8 0.39678929 0.00000000 −6.99540E−021.74616E−02 −2.92734E−03  2.22020E−04 −1.65133E−05 0.00000E+000.00000E+00 0.00000E+00 9 0.18343360 0.00000000 −7.29559E−02 2.27801E−02−3.92842E−03  3.74033E−04 −3.41181E−05 0.00000E+00 0.00000E+000.00000E+00

TABLE 6A Focal length (f) 7.0 mm F-Number 2.5 Half FOV 18° Total tracklength (TTL) 5.9 mm Telephoto ratio (TTL/f) 0.842 Design wavelengths 650nm, 610 nm, 555 nm, 510 nm, 470 nm

TABLE 6B Refractive Abbe Surface Radius Thickness or Index NumberElement (S#) R Shape Separation Material N_(d) V_(d) Object plane 0 INFFLAT INF Aperture 1 INF FLAT 0.0 stop L1 2 1.916 ASP 1.2789 Plastic1.544 56.1 3 −7.423 ASP 0.0500 L2 4 7.127 ASP 0.2300 Plastic 1.632 23.35 1.811 ASP 2.2096 L3 6 10.920 ASP 0.2300 Plastic 1.544 56.1 7 1.899 ASP0.1194 L4 8 2.448 ASP 0.6171 Plastic 1.632 23.3 9 5.206 ASP 0.2200 IRfilter 10 INF FLAT 0.2300 Glass 1.516 64.1 11 INF FLAT 0.7151 Imageplane 12 INF FLAT

TABLE 6C ASPHERIC CONSTANTS Curvature A B C D S# (c) K E F G H 20.52183529 −0.07720366  1.46341E−02 −2.48395E−02  2.22385E−02−9.20416E−03   1.21715E−03 0.00000E+00 0.00000E+00 0.00000E+00 3−0.13472522 0.00000000  2.99796E−02 −1.36208E−02  −6.71745E−03 4.33779E−03 −1.92789E−04 −8.79693E−05  0.00000E+00 0.00000E+00 40.14030600 0.00000000 −8.02143E−02 6.85447E−02 −5.83252E−02  2.89038E−02−4.51377E−03 0.00000E+00 0.00000E+00 0.00000E+00 5 0.55228456−24.72392792  2.36560E−01 −3.47355E−01  3.35652E−01 −1.28634E−01 −7.69847E−03 1.75677E−02 0.00000E+00 0.00000E+00 6 0.09157796 0.00000000−1.34024E−01 −1.89494E−02  3.00211E−02 −1.88323E−02   2.85063E−039.90165E−04 0.00000E+00 0.00000E+00 7 0.52651322 0.00000000 −1.57518E−012.76149E−02 −3.16376E−03  −1.31706E−03   3.92416E−04 0.00000E+000.00000E+00 0.00000E+00 8 0.40842256 0.00000000 −7.89333E−02 2.06852E−02−3.71946E−03  3.25167E−04 −2.96550E−05 0.00000E+00 0.00000E+000.00000E+00 9 0.19207877 0.00000000 −7.32189E−02 1.70840E−02−1.28939E−03  5.83216E−05 −4.62557E−05 0.00000E+00 0.00000E+000.00000E+00

TABLE 7A Focal length (f) 7.0 mm F-Number 2.8 Half FOV 18° Total tracklength (TTL) 6.0 mm Telephoto ratio (TTL/f) 0.857 Design wavelengths 650nm, 610 nm, 555 nm, 510 nm, 470 nm

TABLE 7B Refractive Abbe Surface Radius Thickness or Index NumberElement (S#) R Shape Separation Material N_(d) V_(d) Object plane 0 INFFLAT INF 1 INF FLAT 0.6 Aperture 2 INF FLAT −0.6 stop 3 INF FLAT 0.0 L14 1.581 ASP 0.8579 Plastic 1.544 56.1 5 −19.799 ASP 0.2310 L2 6 15.295ASP 0.2300 Plastic 1.632 23.3 7 2.255 ASP 0.5716 L3 8 −9.153 ASP 0.2300Plastic 1.632 23.3 9 −101.250 ASP 1.7007 L4 10 −2.968 ASP 0.2300 Plastic1.544 56.1 11 4.499 ASP 0.1000 L5 12 4.783 ASP 0.8288 Plastic 1.632 23.313 −8.425 ASP 0.1000 IR filter 14 INF FLAT 0.3000 Glass 1.516 64.1 15INF FLAT 0.6200 Image plane 16 INF FLAT

TABLE 7C ASPHERIC CONSTANTS Curvature A B C D S# (c) K E F G H 40.63235800 −0.18286867  6.89637E−03 −5.97278E−04  7.43545E−03−3.26628E−03  −1.23504E−03 1.19145E−03 0.00000E+00 0.00000E+00 5−0.05050712 0.00000000  2.84470E−02 −3.15439E−03  −1.53315E−02 1.66294E−02 −5.22607E−03 2.83019E−04 0.00000E+00 0.00000E+00 60.06537890 0.00000000 −2.98424E−02 2.90046E−02 1.64261E−02 −2.37258E−03 −8.53628E−03 0.00000E+00 0.00000E+00 0.00000E+00 7 0.44352255−17.25746421  1.53032E−01 −1.76850E−01  4.13733E−01 −2.70598E−01  1.00578E−01 0.00000E+00 0.00000E+00 0.00000E+00 8 −0.109249770.00000000  1.45017E−01 2.18633E−02 6.73353E−02 −5.28971E−02  0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 9 −0.987658E−020.00000000  1.84770E−01 3.47595E−02 3.19226E−02 8.61392E−03 −3.80131E−020.00000E+00 0.00000E+00 0.00000E+00 10 −0.33695059 −2.41215664−5.27029E−02 −1.18014E−03  −7.56505E−04  2.55693E−03 −9.23157E−040.00000E+00 0.00000E+00 0.00000E+00 11 0.22228286 0.00000000−6.18610E−02 4.79993E−03 −2.38680E−03  9.03633E−04 −1.93770E−040.00000E+00 0.00000E+00 0.00000E+00 12 0.20905993 0.00000000−3.36502E−02 7.78012E−03 −1.72940E−04  −5.43850E−05   0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 13 −0.11869224 0.00000000−3.60043E−02 8.75087E−03 8.19760E−04 −1.98969E−04   0.00000E+000.00000E+00 0.00000E+00 0.00000E+00

TABLE 8A Focal length (f) 7.0 mm F-Number 2.8 Half FOV 18° Total tracklength (TTL) 6.0 mm Telephoto ratio (TTL/f) 0.857 Design wavelengths 650nm, 610 nm, 555 nm, 510 nm, 470 nm

TABLE 8B Refractive Abbe Surface Radius Thickness or Index NumberElement (S#) R Shape Separation Material N_(d) V_(d) Object plane 0 INFFLAT INF L1 1 1.581 ASP 0.8579 Plastic 1.544 56.1 2 −19.799 0.0500Aperture 3 INF FLAT 0.1810 stop L2 4 15.295 ASP 0.2300 Plastic 1.63223.3 5 2.255 ASP 0.5716 L3 6 −9.153 ASP 0.2300 Plastic 1.632 23.3 7−101.250 ASP 1.7007 L4 8 −2.968 ASP 0.2300 Plastic 1.544 56.1 9 4.499ASP 0.1000 L5 10 4.783 ASP 0.8288 Plastic 1.632 23.3 11 −8.425 ASP0.1000 IR filter 12 INF FLAT 0.3000 Glass 1.516 64.1 13 INF FLAT 0.6200Image plane 14 INF FLAT

TABLE 8C ASPHERIC CONSTANTS Curvature A B C D S# (c) K E F G H 10.63235800 −0.18286867 −0.18286867 6.89637E−03 7.43545E−03 −3.26628E−03 −1.23504E−03 1.19145E−03 0.00000E+00 0.00000E+00 2 −0.050507120.00000000  2.84470E−02 −3.15439E−03  −1.53315E−02  1.66294E−02−5.22607E−03 2.83019E−04 0.00000E+00 0.00000E+00 4 0.06537890 0.00000000−2.98424E−02 2.90046E−02 1.64261E−02 −2.37258E−03  −8.53628E−030.00000E+00 0.00000E+00 0.00000E+00 5 0.44352255 −17.25746421 1.53032E−01 −1.76850E−01  4.13733E−01 −2.70598E−01   1.00578E−010.00000E+00 0.00000E+00 0.00000E+00 6 −0.10924977 0.00000000 1.45017E−01 2.18633E−02 6.73353E−02 −5.28971E−02   0.00000E+000.00000E+00 0.00000E+00 0.00000E+00 7 −0.987658E−02 0.00000000 1.84770E−01 3.47595E−02 3.19226E−02 8.61392E−03 −3.80131E−020.00000E+00 0.00000E+00 0.00000E+00 8 −0.33695059 −2.41215664−5.27029E−02 −1.18014E−03  −7.56505E−04  2.55693E−03 −9.23157E−040.00000E+00 0.00000E+00 0.00000E+00 9 0.22228286 0.00000000 −6.18610E−024.79993E−03 −2.38680E−03  9.03633E−04 −1.93770E−04 0.00000E+000.00000E+00 0.00000E+00 10 0.20905993 0.00000000 −3.36502E−027.78012E−03 −1.72940E−04  −5.43850E−05   0.00000E+00 0.00000E+000.00000E+00 0.00000E+00 11 −0.11869224 0.00000000 −3.60043E−028.75087E−03 8.19760E−04 −1.98969E−04   0.00000E+00 0.00000E+000.00000E+00 0.00000E+00

Example Computing Device

FIG. 17 illustrates an example computing device, referred to as computersystem 2000, that may include or host embodiments of the camera asillustrated in FIGS. 1 through 16. In addition, computer system 2000 mayimplement methods for controlling operations of the camera and/or forperforming image processing of images captured with the camera. Indifferent embodiments, computer system 2000 may be any of various typesof devices, including, but not limited to, a personal computer system,desktop computer, laptop, notebook, tablet or pad device, slate, ornetbook computer, mainframe computer system, handheld computer,workstation, network computer, a camera, a set top box, a mobile device,a wireless phone, a smartphone, a consumer device, video game console,handheld video game device, application server, storage device, atelevision, a video recording device, a peripheral device such as aswitch, modem, router, or in general any type of computing or electronicdevice.

In the illustrated embodiment, computer system 2000 includes one or moreprocessors 2010 coupled to a system memory 2020 via an input/output(I/O) interface 2030. Computer system 2000 further includes a networkinterface 2040 coupled to I/O interface 2030, and one or moreinput/output devices 2050, such as cursor control device 2060, keyboard2070, and display(s) 2080. Computer system 2000 may also include one ormore cameras 2090, for example one or more telephoto cameras asdescribed above with respect to FIGS. 1 through 16, which may also becoupled to I/O interface 2030, or one or more telephoto cameras asdescribed above with respect to FIGS. 1 through 16 along with one ormore other cameras such as conventional wide-field cameras.

In various embodiments, computer system 2000 may be a uniprocessorsystem including one processor 2010, or a multiprocessor systemincluding several processors 2010 (e.g., two, four, eight, or anothersuitable number). Processors 2010 may be any suitable processor capableof executing instructions. For example, in various embodimentsprocessors 2010 may be general-purpose or embedded processorsimplementing any of a variety of instruction set architectures (ISAs),such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitableISA. In multiprocessor systems, each of processors 2010 may commonly,but not necessarily, implement the same ISA.

System memory 2020 may be configured to store program instructions 2022and/or data 2032 accessible by processor 2010. In various embodiments,system memory 2020 may be implemented using any suitable memorytechnology, such as static random access memory (SRAM), synchronousdynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type ofmemory. In the illustrated embodiment, program instructions 2022 may beconfigured to implement various interfaces, methods and/or data forcontrolling operations of camera 2090 and for capturing and processingimages with integrated camera 2090 or other methods or data, for exampleinterfaces and methods for capturing, displaying, processing, andstoring images captured with camera 2090. In some embodiments, programinstructions and/or data may be received, sent or stored upon differenttypes of computer-accessible media or on similar media separate fromsystem memory 2020 or computer system 2000.

In one embodiment, I/O interface 2030 may be configured to coordinateI/O traffic between processor 2010, system memory 2020, and anyperipheral devices in the device, including network interface 2040 orother peripheral interfaces, such as input/output devices 2050. In someembodiments, I/O interface 2030 may perform any necessary protocol,timing or other data transformations to convert data signals from onecomponent (e.g., system memory 2020) into a format suitable for use byanother component (e.g., processor 2010). In some embodiments, I/Ointerface 2030 may include support for devices attached through varioustypes of peripheral buses, such as a variant of the Peripheral ComponentInterconnect (PCI) bus standard or the Universal Serial Bus (USB)standard, for example. In some embodiments, the function of I/Ointerface 2030 may be split into two or more separate components, suchas a north bridge and a south bridge, for example. Also, in someembodiments some or all of the functionality of I/O interface 2030, suchas an interface to system memory 2020, may be incorporated directly intoprocessor 2010.

Network interface 2040 may be configured to allow data to be exchangedbetween computer system 2000 and other devices attached to a network2085 (e.g., carrier or agent devices) or between nodes of computersystem 2000. Network 2085 may in various embodiments include one or morenetworks including but not limited to Local Area Networks (LANs) (e.g.,an Ethernet or corporate network), Wide Area Networks (WANs) (e.g., theInternet), wireless data networks, some other electronic data network,or some combination thereof. In various embodiments, network interface2040 may support communication via wired or wireless general datanetworks, such as any suitable type of Ethernet network, for example;via telecommunications/telephony networks such as analog voice networksor digital fiber communications networks; via storage area networks suchas Fibre Channel SANs, or via any other suitable type of network and/orprotocol.

Input/output devices 2050 may, in some embodiments, include one or moredisplay terminals, keyboards, keypads, touchpads, scanning devices,voice or optical recognition devices, or any other devices suitable forentering or accessing data by computer system 2000. Multipleinput/output devices 2050 may be present in computer system 2000 or maybe distributed on various nodes of computer system 2000. In someembodiments, similar input/output devices may be separate from computersystem 2000 and may interact with one or more nodes of computer system2000 through a wired or wireless connection, such as over networkinterface 2040.

As shown in FIG. 17, memory 2020 may include program instructions 2022,which may be processor-executable to implement any element or action tosupport integrated camera 2090, including but not limited to imageprocessing software and interface software for controlling camera 2090.In at least some embodiments, images captured by camera 2090 may bestored to memory 2020. In addition, metadata for images captured bycamera 2090 may be stored to memory 2020.

Those skilled in the art will appreciate that computer system 2000 ismerely illustrative and is not intended to limit the scope ofembodiments. In particular, the computer system and devices may includeany combination of hardware or software that can perform the indicatedfunctions, including computers, network devices, Internet appliances,PDAs, wireless phones, pagers, video or still cameras, etc. Computersystem 2000 may also be connected to other devices that are notillustrated, or instead may operate as a stand-alone system. Inaddition, the functionality provided by the illustrated components mayin some embodiments be combined in fewer components or distributed inadditional components. Similarly, in some embodiments, the functionalityof some of the illustrated components may not be provided and/or otheradditional functionality may be available.

Those skilled in the art will also appreciate that, while various itemsare illustrated as being stored in memory or on storage while beingused, these items or portions of them may be transferred between memoryand other storage devices for purposes of memory management and dataintegrity. Alternatively, in other embodiments some or all of thesoftware components may execute in memory on another device andcommunicate with the illustrated computer system 2000 via inter-computercommunication. Some or all of the system components or data structuresmay also be stored (e.g., as instructions or structured data) on acomputer-accessible medium or a portable article to be read by anappropriate drive, various examples of which are described above. Insome embodiments, instructions stored on a computer-accessible mediumseparate from computer system 2000 may be transmitted to computer system2000 via transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as a network and/or a wireless link. Various embodiments mayfurther include receiving, sending or storing instructions and/or dataimplemented in accordance with the foregoing description upon acomputer-accessible medium. Generally speaking, a computer-accessiblemedium may include a non-transitory, computer-readable storage medium ormemory medium such as magnetic or optical media, e.g., disk orDVD/CD-ROM, volatile or non-volatile media such as RAM (e.g. SDRAM, DDR,RDRAM, SRAM, etc.), ROM, etc. In some embodiments, a computer-accessiblemedium may include transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as network and/or a wireless link.

The methods described herein may be implemented in software, hardware,or a combination thereof, in different embodiments. In addition, theorder of the blocks of the methods may be changed, and various elementsmay be added, reordered, combined, omitted, modified, etc. Variousmodifications and changes may be made as would be obvious to a personskilled in the art having the benefit of this disclosure. The variousembodiments described herein are meant to be illustrative and notlimiting. Many variations, modifications, additions, and improvementsare possible. Accordingly, plural instances may be provided forcomponents described herein as a single instance. Boundaries betweenvarious components, operations and data stores are somewhat arbitrary,and particular operations are illustrated in the context of specificillustrative configurations. Other allocations of functionality areenvisioned and may fall within the scope of claims that follow. Finally,structures and functionality presented as discrete components in theexample configurations may be implemented as a combined structure orcomponent. These and other variations, modifications, additions, andimprovements may fall within the scope of embodiments as defined in theclaims that follow.

1.-20. (canceled)
 21. A telephoto lens system, comprising: a pluralityof refractive lens elements arranged along an optical axis of thecamera, wherein at least one surface of at least one of the plurality oflens elements is aspheric, wherein the plurality of lens elementsinclude at least a first lens element, a second lens element, a thirdlens element, and a fourth lens element, and wherein the fourth lenselement from the object side of the camera has a concave image sidesurface; wherein the lens system has effective focal length f whereintotal track length (TTL) of the lens system is 6.0 millimeters or less,and wherein telephoto ratio (TTL/f) of the lens system is within a rangeof 0.74 to 1.0; and wherein the lens system configured to refract lightfrom an object field located in front of the first lens element to forman image at an image plane behind a last lens element of the pluralityof lens elements.
 22. The telephoto lens system as recited in claim 21,wherein the effective focal length f of the lens system is within arange of 6.0 millimeters to 8.0 millimeters, and wherein focal ratio ofthe lens system is within a range of 2.4 to 10.0.
 23. The telephoto lenssystem as recited in claim 21, wherein the effective focal length f ofthe lens system is 7.0 millimeters, and wherein focal ratio of the lenssystem is 2.8.
 24. The telephoto lens system as recited in claim 21,wherein the telephoto lens system further comprises an aperture stoplocated either at or in front of the first lens element of the lenssystem or between the first lens element and the second lens element ofthe lens system.
 25. The telephoto lens system as recited in claim 24,wherein the aperture stop is adjustable to provide a focal ratio withina range of 2.4 to
 10. 26. The telephoto lens system as recited in claim21, wherein at least two of the plurality of lens elements are composedof a first plastic material, and wherein at least two others of theplurality of lens elements are composed of a second plastic materialwith different optical characteristics than the first plastic material.27. The telephoto lens system as recited in claim 21, wherein theplurality of lens elements includes, in order along the optical axisfrom the object side to the image side: the first lens element withpositive refractive power having a convex object side surface; thesecond lens element with negative refractive power; the third lenselement with negative refractive power having a concave object sidesurface; the fourth lens element with negative refractive power having aconcave object side surface; and a fifth lens element with positiverefractive power having a convex image side surface.
 28. The telephotolens system as recited in claim 27, wherein the first lens element is abiconvex lens, and wherein focal length f1 of the first lens elementsatisfies the condition 0.35<f1/f<0.45.
 29. The telephoto lens system asrecited in claim 27, wherein the second lens element has either a convexobject side surface or a concave object side surface, and wherein one orboth of the third lens element and the fourth lens element are biconcavelenses.
 30. The telephoto lens system as recited in claim 21, whereinthe first lens element and the second lens element form a Gaussiandoublet of positive refractive power and focal length f12 that satisfiesthe relation 0.75<f12/f<1.0, and wherein the third lens element and thefourth lens element form an air-spaced doublet of negative refractivepower and focal length f34 that satisfies the relation −2.0<f34/f<−1.0.31. A telephoto lens system, comprising: a plurality of refractive lenselements arranged along an optical axis of the camera, wherein at leastone surface of at least one of the plurality of lens elements isaspheric, wherein the plurality of lens elements include at least afirst lens element, a second lens element, a third lens element, and afourth lens element, and wherein the fourth lens element from the objectside of the camera has a concave image side surface; wherein thetelephoto lens system has effective focal length f within a range of 6.0millimeters to 8.0 millimeters, wherein total track length (TTL) of thetelephoto lens system is 7.0 millimeters or less, and wherein telephotoratio (TTL/f) of the lens system is within a range of 0.74 to 1.0; andwherein the lens system configured to refract light from an object fieldlocated in front of a first lens element of the plurality of lenselements to form an image at an image plane behind a last lens elementof the plurality of lens elements.
 32. The telephoto lens system asrecited in claim 31, wherein focal ratio of the lens system is within arange of 2.4 to 10.0.
 33. The telephoto lens system as recited in claim31, wherein the telephoto lens system further comprises an aperture stoplocated either at or in front of the first lens element of the lenssystem or between the first lens element and the second lens element ofthe lens system.
 34. The telephoto lens system as recited in claim 33,wherein the aperture stop is adjustable to provide a focal ratio withina range of 2.4 to
 10. 35. The telephoto lens system as recited in claim31, wherein at least two of the plurality of lens elements are composedof a first plastic material, and wherein at least two others of theplurality of lens elements are composed of a second plastic materialwith different optical characteristics than the first plastic material.36. The telephoto lens system as recited in claim 31, wherein theplurality of lens elements includes, in order along the optical axisfrom the object side to the image side: the first lens element withpositive refractive power having a convex object side surface; thesecond lens element with negative refractive power having a convexobject side surface; the third lens element with positive refractivepower having a convex object side surface; the fourth lens element withnegative refractive power having a concave object side surface; and afifth lens element with positive refractive power having a convex imageside surface.
 37. The telephoto lens system as recited in claim 36,wherein the fifth lens element has positive focal length f5, vertexradii of curvature R10 and R11, and satisfies the conditions(0.75<f5/f<1.2) and (−1<R10/R11<0).
 38. The telephoto lens system asrecited in claim 31, wherein the first lens element and the second lenselement form a Gaussian doublet of positive refractive power and focallength f12 that satisfies the relation 0.75<f12/f<1.0, and wherein thethird lens element and the fourth lens element form an air-spaceddoublet of negative refractive power and focal length f34 that satisfiesthe relation −2.0<f34/f<−1.0.
 39. A camera module, comprising: aphotosensor configured to capture light projected onto a surface of thephotosensor; and a telephoto lens system configured to refract lightfrom an object field located in front of the camera to form an image ofa scene at an image plane at or near the surface of the photosensor,wherein the lens system comprises a plurality of refractive lenselements arranged along an optical axis of the camera, wherein at leastone surface of at least one of the plurality of lens elements isaspheric, wherein the plurality of lens elements include at least afirst lens element, a second lens element, a third lens element, and afourth lens element, and wherein the fourth lens element from the objectside of the camera has a concave image side surface; wherein thetelephoto lens system has effective focal length f within a range of 6.0millimeters to 8.0 millimeters, wherein total track length (TTL) of thetelephoto lens system is 7.0 millimeters or less, and wherein telephotoratio (TTL/f) of the lens system is within a range of 0.74 to 1.0. 40.The camera module as recited in claim 39, wherein the telephoto lenssystem further comprises an aperture stop located either at or in frontof the first lens element of the lens system or between the first lenselement and the second lens element of the lens system.